A Survey of Licensed Wisconsin Optometrists on
Lutein and Zeaxanthin and Eye Health
Tara Larson
A Research Paper
Submitted in Partial Fulfillment of the
Requirements for the
Master of Science Degree
in
Food and Nutritional Sciences
Approved: 2 Semester Credits
/
Janice Coker, Ph.D.
Research Advisor
The Graduate School
University of Wisconsin-Stout
December, 2006
The Graduate School
University of Wisconsin-Stout
Menomonie, WI
Author:
Larson, Tara A.
Title:
A Survey of Licensed Wisconsin Optometrists on Lutein and Zeaxanthin and Eye
Health
Graduate Degree1 Major: MS Food and Nutritional Sciences1 Human Nutritional Science
Research Advisor:
Janice Coker, Ph.D.
MonthNear:
December, 2006
Number of Pages:
100
Style Manual Used: American Psychological Association, sthedition
ABSTRACT
Age-related macular degeneration (AMD) and age-related cataract (cataract) are two of
the leading causes of vision impairment and blindness in the U.S. (Prevent Blindness America,
2002). The rate of vision impairment and blindness is expected to double in the next 30 years.
Lutein and/or high-dose antioxidants reduce(s) the risk of AMD or improve(s) visual function in
patients with AMD (Seddon, Ajani, et al., 1994; Age-Related Eye Disease Study Group [AREDS
Group], 2001a; Richer et al., 2004).
The purpose of this study was to determine the perceptions, recommendations, and
educational or informational materials of optometrists on lutein and zeaxanthin and eye health. A
20-item survey was developed and mailed to 300 randomly chosen licensed optometrists in
Wisconsin. The response rate was 42.3%.
Most respondents (77.2%) were moderately to very informed about the relationship
between lutein and zeaxanthin and eye health. The information on lutein and zeaxanthin and eye
health was adequate for 78.0% of respondents to make recommendations to patients, A multivitamidmineral supplement was the most recommended supplement (9 1.3%) with a lutein or
zeaxanthin supplement (86.6%), spinach or other foods rich in lutein and zeaxanthin (85.8%),
and a zinc supplement (85.0%) following closely behind. Most respondents distributed
educational or informational materials to patients at their practice (79.5%) while about half
(50.5%) of these respondents had educational or informational materials on lutein and
zeaxanthin.
An increased demand fiom patients and insurers to provide nutrition education is
anticipated. Patient educational materials or dietitian referrals are key strategies to provide this
education. Future research should address the barriers of optometrists in obtaining information
on nutrition for eye health.
The Graduate School
University of Wisconsin-Stout
Menomonie, WI
Acknowledgements
There are several people who contributed to this research project that deserve thanks and
recognition. First, I would like to thank Janice Coker, Ph.D., for her wisdom, encouragement and
direction throughout the research process. Second, I would like to express my gratitude to
Nicholas R. Gilmore, O.D., James B. Kivlin, O.D., and James M. Ulesich, O.D. for their
willingness to offer advice to improve the quality of my survey. Third, I would like to
acknowledge John Warren, O.D. and Scott Jens, O.D., F.A.A.O. for their interest in the results of
this study and assistance in publishing a reminder to complete the survey in the Wisconsin
Optometric Association's monthly member newsletter. Next, I appreciate the optometrists who
completed and returned the surveys and made the results possible. Lastly, I am grateful for my
parents and siblings for their support and encouragement and my coworkers at Trinity Regional
Medical Center for covering for me while I worked on my research paper.
TABLE OF CONTENTS
..............................................................................................................
.Page
..
ABSTRACT..................................................................................................-11
List of Tables................................................................................................
...
vlll
Chapter I: Introduction........................................................................................ 1
Statement of the Problem ........................................................................... -3
Research Objectives..................................................................................3
Assumptions of the Study ............................................................................4
Definition of Terms...................................................................................4
Limitations of the Study ..............................................................................5
Methodology.......................................................................................... 5
Chapter 11: Literature Review ................................................................................6
Introduction ........................................................................................... -6
Vision Impairment, Blindness and Age-Related Eye Disease ...................................6
Age-Related Macular Degeneration (AMD)...................................................... 7
Age-Related Cataract (Cataract)...................................................................9
Dietary Intake, Serum Concentrations and Age-related Eye Disease ........................ 11
Antioxidant Supplements and Intake and Age-Related Cataract..............................14
Macular Pigment Density .......................................................................... 16
Aging, Antioxidant Concentrations and Age-Related Cataract..............................20
Major Clinical Trials..............................................................................-22
L utein and Zeaxanthin: Sources, Bioavailability and Metabolism ........................... 25
Dietary Recommendations and Intake ............................................................26
Safety and Use ofDietary Supplements .......................................................... 27
Optometry and Nutrition Education .............................................................. 28
Chapter 111: Methodology ................................................................................... 30
Introduction .......................................................................................... 30
Subject Selection and Description ................................................................ 30
Instrumentation ......................................................................................30
Data Collection Procedures ....................................................................... 33
Data Analysis ....................................................................................... -33
Limitations ...........................................................................................33
Chapter IV: Results .........................................................................................
-35
Introduction ..........................................................................................35
Demographic Information .........................................................................35
Item Analysis ........................................................................................ -37
Information on Lutein and Zeaxanthin and Eye Health .......................................38
Nutritional Recommendations to Patients ....................................................... 41
Educational or Informational Materials Distributed to Patients .............................44
Selected Item Response by Gender ............................................................... 49
Response Analysis within Items ..................................................................-53
Research Objectives................................................................................. 60
Chapter V: Discussion ...................................................................................................................64
Introduction .......................................................................................... 64
Discussion ...........................................................................................
-64
Limitations ........................................................................................... 66
vii
Conclusions ......................................................................................... -67
Recommendations ..................................................................................-69
References.....................................................................................................72
Appendix A: Cover Letter.................................................................................-82
Appendix B: Survey Instrument...........................................................................83
Appendix C: Reminder Postcard...........................................................................
87
Appendix D: Comments from Respondents.............................................................. 88
List of Tables
Table 1 : Prevalence of advanced age-related macular degeneration (AMD) by age. gender and
race .................................................................................................... 9
Table 2: Prevalence of cataract by age. gender and race ................................................1 1
Table 3: Contents of the OcuPowerB supplement taken during the LAST study...................24
Table 4: How many years have you been practicing optometry?...................................... 36
Table 5: What is your age?.................................................................................. 37
Table 6: How informed do you feel about the relationship between lutein and zeaxanthin and eye
health? ............................................................................................... 38
Table 7: Where have you obtained information on the relationship between lutein and zeaxanthin
and eye health? .................................................................................... 39
Table 8: Using a scale of 1 to 3, please rank your top 3 most preferred sources of information on
lutein and zeaxanthin and eye health .......................................................... 40
Table 9: I recommend [foods or supplements] to patients [subgroup]...............................42
Table 10: I recommend [foods or supplements] to [any] patients.................................... 44
Table 1 1 : Where have you obtained your educational or informational materials on lutein and
zeaxanthin?......................................................................................... 46
Table 12: If you currently do not distribute educational or informational materials on lutein and
zeaxanthin, using a scale of 1 to 3, please rank your top 3 reasons for not distributing
educational or informational materials on lutein and zeaxanthin...........................48
Table 13: How important is it to you to have educational or informational materials on lutein and
zeaxanthin to give to your patients? ............................................................49
Table 14: How informed do you feel about the relationship between lutein and zeaxanthin and
. .
eye health? within gender.. ...................................................................... -50
Table 15: Is the information on lutein and zeaxanthin and eye health adequate for you to make
recommendations to patients? within gender.. .............................................. ..50
Table 16: I recommend [foods or supplements] to patients within gender.. .......................... 5 1
Table 17: Do you currently distribute educational or informational materials to patients at your
. .
practice? within gender.. ........................................................................ -52
Table 18: Do you have educational or informational materials on lutein and zeaxanthin? within
gender. ............................................................................................. .52
Table 19: How important is it to you to have educational or informational materials on lutein and
zeaxanthin to give to your patients? within gender.. ........................................ .53
Table 20: How informed do you feel about the relationship between lutein and zeaxanthin and
eye health? within Where have you obtained information on the relationship between
lutein and zeaxanthin and eye health?. .........................................................54
Table 2 1: How informed do you feel about the relationship between lutein and zeaxanthin and
eye health? within Is the information on lutein and zeaxanthin and eye health adequate
for you to make recommendations to patients?. ............................................... 55
Table 22: Is the information on lutein and zeaxanthin and eye health adequate for you to make
recommendations to patients? within I recommend spinach or other foods rich in lutein
and zeaxanthin to patients.. ......................................................................56
Table 23: Is the information on lutein and zeaxanthin and eye health adequate for you to make
recommendations to patients? within I recommend a lutein or zeaxanthin supplement to
patients. ............................................................................................ -56
Table 24: Patients at risk or diagnosed with AMD within I recommend [foods or supplements] to
patients.. .......................................................................................... -57
Table 25: Do you have educational or informational materials on lutein and zeaxanthin? within I
recommend spinach or other foods rich in lutein and zeaxanthin to patients.. .......... .58
Table 26: Do you have educational or informational materials on lutein and zeaxanthin? within I
recommend a lutein or zeaxanthin supplement to patients.. ............................... .58
Table 27: Do you have educational or informational materials on lutein and zeaxanthin? within Is
the information on lutein and zeaxanthin and eye health adequate for you to make
recommendations to patients?. ................................................................. -59
Table 28: How important is it to you to have educational or informational materials on lutein and
zeaxanthin to give to your patients? within Do you have educational or informational
materials on lutein and zeaxanthin?. .......................................................... .60
Chapter I: Introduction
Vision impairment and blindness due to age-related eye disease is increasing (Prevent
Blindness America, 2002). Age-related macular degeneration (AMD) is the leading cause of
blindness in persons age 60 and older in the U.S. while cataract is the leading cause of blindness
in the world (National Eye Institute [NEI], 2002, March). Blindness negatively affects both an
individual's quality of life and the national economy (Prevent Blindness America). The
carotenoids lutein and zeaxanthin may play a preventive role in age-related blindness as
discussed below.
Lutein and zeaxanthin are the only two carotenoids concentrated in the macula
(Snodderly, 1995) and lens of the eye (Yeum, Taylor, Tang, & Russell, 1995). These two yellow
plant pigments are called the macular pigment (Pratt, 1999). Macular pigment density (MPD) is
positively associated with visual acuity (Hammond, Wooten, & Snodderly, 1998) and inversely
associated with lens optical density (LOD) (Berendschot et al., 2002). Studies have shown that
MPD can be increased through diet (Harnmond, Johnson, et al., 1997) or supplementation
(Landrum et al., 1997; Berendschot et al., 2000). A higher dietary intake of spinach or collard
greens, foods rich in lutein and zeaxanthin, has been associated with a lower risk of AMD
(Seddon, Ajani, et al., 1994). Brown et al. (1999) and Chasm-Taber et al. (1999) found a 19%
and 22% lower risk for cataract extraction in men and women, respectively for those with the
highest intake of lutein and zeaxanthin intake compared to those in the lowest quintile.
In addition to reducing the risk of AMD and cataract, lutein, zeaxanthin andfor
antioxidants have reduced the risk of progression to advanced AMD (AREDS Group, 2001a) and
have improved visual acuity in AMD patients (Richer et al., 2004). This has led to the
manufacture of lutein and zeaxanthin as a dietary supplement (Kreuzer, n.d.) and to lutein as the
most popular herbal and other natural dietary supplement mainly in the form of a multi-vitamin
preparation (Kelly et al., 2005).
Natural sources of lutein and zeaxanthin include kale, collard greens and spinach as the
highest sources (United States Department of Agriculture [USDA], n.d.). Healthy People 2010
(Food and Drug Administration [FDA] & National Institutes of Health [NIH], 2000) and The
Dietary Guidelines for Americans (United States Department of Health and Human Services
[USDHHS], 2005) both recommend frequent consumption of dark green vegetables. Despite the
5 A Day guidelines (National Cancer Institute [NCI], 2001), most Americans are not meeting the
recommended number of h i t and vegetable servings (Centers for Disease Control and
Prevention [CDC], 2006; FDA & NIH). The Multi-Center Eye Disease Case-Control Study
found a median intake of 1.7 mg lutein per day (Seddon, Ajani, et al., 1994) while 6 mg per day
has been shown to reduce risk for AMD (Mares-Perlman et al., 2001). The increasing rate of
AMD and cataract may possibly be affected by the low consumption of dark green vegetables
with lutein and zeaxanthin.
Although the role of lutein in prevention of age-related eye disease is still uncertain (NEI,
2002, July), optometrists can promote the intake of dark green vegetables as it is a national
public health objective (FDA & NIH, 2000). With their expertise in eye care, optometrists are
uniquely positioned to provide nutrition education for eye health. They may also provide credible
information to guide patients on the use of nutritional supplements for eye health. With
optometrists' lack of financial incentive and time for preventive health care, educational or
informational materials or a referral to a dietitian may be an effective way to promote a healthy
diet and address patient nutritional concerns.
Statement of the Problem
Studies showing a relationship between diets high in lutein and zeaxanthin and eye health
along with an increased popularity of lutein supplements have provided a challenge for
optometrists to take on a non-traditional role of nutrition education. The purpose of this study
was to describe how the confidence of licensed Wisconsin optometrists in the relationship
between diets high in lutein and zeaxanthin and eye health influenced their clinical practice.
First, this study was conducted to gain an understanding of how optometrists viewed the current
state of literature on nutrition and eye health. Secondly, since it is most likely that patients would
seek out nutrition advice for eye health from their eye doctor, knowing the nutritional
recommendations of optometrists can assist patients in obtaining credible information. Third,
patient educational materials can compliment advice given in the office. Assessing the
availability and perceived importance of educational materials can help public health
professionals determine the need to develop these materials.
Research Objectives
The specific research objectives were to:
1. Evaluate the awareness, sources of information, and confidence of Wisconsin
optometrists on the relationship between diets high in lutein and zeaxanthin and eye
health;
2. Determine the nutritional recommendations of Wisconsin optometrists for the
prevention or treatment of AMD and cataract;
3. Assess the availability and importance of educational materials on lutein and
zeaxanthin to Wisconsin optometrists;
4. Summarize the perceptions of Wisconsin optometrists of lutein and zeaxanthin and
eye health; and
5. Describe the demographic characteristics of Wisconsin optometrists.
Assumptions o f the Study
It was assumed that optometrists who completed the survey were honest in their
responses and that their answers reflected their current practices and feelings.
Definition of Terms
Snellen Chart: Chart containing rows of letters, numbers or symbols of a standardized
size used to test visual acuity usually at 20 feet (Triad Publishing Company, 2006).
20/20 vision: Normal sharpness or clarity of vision (visual acuity) at a distance of 20 feet.
This is only one indictor of visual function. Other indicators include side vision, eye
coordination, depth perception, focusing ability and color vision (American Optometric
Association [AOA], 2006b).
Vision impairment: Vision of 20140 or worse in the better eye with best correction
(Prevent Blindness America, 2002) often referred to as low vision (The Eye Diseases
Prevalence Research Group [EDPRG], 2004a).
Legal blindness: In the United States, vision of 201200 in the better eye with best
possible correction (AOA, 2006a).
Age-related eye disease (ARED): The main causes of vision impairment and blindness in
the U.S., which includes age-related macular degeneration, cataract, diabetic retinopathy
and glaucoma (Prevent Blindness America, 2002).
Age-related macular degeneration (AMD): A degenerative disorder of the retina at the
area of highest concentration of photoreceptors (macula), which leads to legal blindness
(Snodderly, 1995).
Age-related cataract: The opacification and dysfunction of the lens of the eye from the
accumulated effects of photooxidation and aging (Taylor, Jacques, & Epstein, 1995).
Limitations of the Study
This study was limited by the optometrists who chose to respond to the survey and the
design of the survey questions. The responses received may not accurately represent the practices
and feelings of licensed Wisconsin optometrists overall. Data may be biased toward optometrists
who feel strongly in favor of lutein supplements. While the Age-Related Eye Disease Study
(AREDS), a major eye study in which optometrists are likely to base their nutritional
recommendations, evaluated the effect of high-dose vitamins and minerals taken together on the
progression of AMD and age-related cataract, the survey asked about these nutrients individually
and did not separate recommendations for patients at different stages of AMD.
Methodology
A 20-item survey was developed after review of the literature on lutein and zeaxanthin,
antioxidants, AMD and cataract. The survey was pre-tested by three licensed optometrists. The
survey was mailed to 300 randomly chosen licensed optometrists in Wisconsin in May 2003.
Data were entered and analyzed using SPSS version 11.5 for Windows.
Chapter 11: Literature Review
Introduction
This chapter will discuss lutein and zeaxanthin in age-related eye disease (ARED). The
first section will describe the occurrence of visual impairment, blindness, age-related macular
degeneration (AMD) and cataract. The next section will review the current observational and
clinical research on lutein and zeaxanthin in AMD and cataract. The last section will examine
lutein and zeaxanthin in foods or supplements and factors that may influence their digestion and
safety.
Vision Impairment, Blindness and Age-Related Eye Disease
An estimated 3.4 million Americans age 40 and older (2.9%) are visually impaired while
more than one million of this group (0.9%) is considered legally blind (Prevent Blindness
America, 2002). Women are affected more by vision impairment and blindness than men.
Approximately 3.5% of women and 2.1% of men age 40 and older in the United States are
visually impaired while 1.1% of women and 0.6% of men are blind. There is a higher incidence
of vision impairment in the White race (3.1%) compared to the Black (2.2%), Hispanic (1.9%) or
other races (1.8%). When the percent of the total cases of vision impairment due to blindness is
compared by race, Blacks are the most affected by blindness (42.2%) and Hispanics are the least
affected (13.6%). Vision impairment and blindness tends to increase considerably after age 75.
The rate of vision impairment and blindness is expected to double in the next 30 years due to the
aging Baby Boomer generation.
The above rates of vision impairment and blindness may appear small while blindness
among races may appear high. To better understand these statistics, it should be noted that the
reported rates of vision impairment include the total U.S. population age 40 and older who have
vision of 20140 or worse in the better eye even after correction. Similarly, the reported rates of
blindness include the total population age 40 and over who are legally blind. In contrast, the
reported rates of blindness among races include only blind persons age 40 and older in the U.S.
Therefore, the rates of vision impairment and blindness may seem low because of less vision
impairment and blindness among the middle aged (age 40 to 70) while the rates of blindness may
appear elevated among races because these are expressed as percentage of the total blind rather
than percentage of the total race age 40 and older.
The four leading causes of vision impairment and blindness in the U.S. are AMD,
cataract, diabetic retinopathy and glaucoma (Prevent Blindness America, 2002). These
conditions are collectively referred to as ARED. This paper will concentrate on AMD and
cataract. When speaking of cataract, age-related cataract is assumed. AMD is the main cause of
blindness in persons age 60 and older in the United States while cataract is the primary cause of
blindness in the world (NEI, 2002, March).
Blindness from AMD and cataract affects quality of life by restricting one's ability to
read, write, drive a car and perform other activities of daily living. Brody et al. (2001) found
32.5% of participants with late AMD (20160 vision) have depression, which was twice the rate of
community-dwelling older adults. Vision loss also affects the national economy. It is expected
that the federal government will lose four billion dollars annually in benefits and taxable income
due to blindness and vision impairment (Prevent Blindness America, 2002).
Age-Related Macular Degeneration (AMD)
The two forms of AMD are dry AMD and wet AMD (Prevent Blindness America, 2002).
The most common form, dry AMD, usually progresses slowly in the early stage (Gottlieb, 2002).
Early dry AMD is characterized by fatty, yellow deposits called drusen (Prevent Blindness
America) within the macula that are large and numerous (Gottlieb). The macula is the central
area of the retina with the highest concentration of light-receptor cells, which provides sharp
central vision. Late stage dry AMD involves atrophy of the retinal pigment epithelium
(geographic atrophy), which can cause loss of central vision. While only about 15% of AMD
cases are the wet form (Gottlieb), all of these are considered late stage because of the severe
vision loss due to the growth of new blood vessels (neovascularization) that leak and form scar
tissue (Prevent Blindness America).
Approximately 1.6 million Americans age 50 and older (2.2%) have late AMD (Prevent
Blindness America, 2002; "U.S. Census 2000"). Females (2.5%) are affected slightly more than
males (1.7%). The incidence of late AMD in Wisconsin is estimated at 2.4% with 2.9% of
females and 1.9% of males affected, which is slightly higher than the national rate. The Beaver
Dam, Wisconsin population had a prevalence of late AMD of 1.6% among persons age 43 to 86
years (Klein, Klein, & Linton, 1992). Late AMD is most common in the White race (2.4%)
followed by Blacks (l.4%), Hispanics (1.2%) and other races (1.2%). The Eye Diseases
Prevalence Research Group (EDPRG, 2004a) found AMD to be the leading cause of blindness in
White Americans.
The rates of AMD are better understood when data are summarized by age, gender, and
race (See Table 1). According to The Eye Diseases Prevalence Research Group (2004b) data,
females have a higher rate of advanced ANID than males of the same race. Although black
females have a higher rate in the earlier years (ages 50 to 69), white females have a higher rate in
the later years (ages 70 to 2 80). This is due to a sharp increase among white females beginning
at age 70 compared to black females who have a more moderate increase with age. Similarly,
white males show a pattern of sharp increase of advanced AMD beginning at age 70 in contrast
to black males who continue with a gradual increase with age.
Table 1
Prevalence of advanced age-related macular degeneration
(AMD) by age, gender and race
Rate Der 100 individuals (95% CI)
GenderIAge, years
White Race
~ i a c k~ a c k
Females
50-54
0.20 (0.17-0.24)
0.68 (0.57-0.80)
55-59
0.22 (0.20-0.24)
0.82 (0.71-0.96)
60-64
0.35 (0.33-0.39)
1 .OO (0.86-1.15)
65-69
0.70 (0.64-0.76)
1.21 (1.04-1.42)
70-74
1.52 (1.4.1-1.64)
1.47 (1.23-1.76)
75-79
3.44 (3.22-3.69)
1.79 (1.45-2.21)
> 80
16.39 (14.97-17.91)
2.44 (1.85-3.20)
Males
50-54
0.34 (0.23-0.50)
0.42 (0.25-0.70)
55-59
0.41 (0.34-0.50)
0.52 (0.33-0.80)
60-64
0.63 (0.53-0.75)
0.63 (0.42-0.95)
65-69
1.08 (0.91-1.29)
0.77 (0.50-1.18)
70-74
1.98 (1.69-2.32)
0.93 (0.57-1.53)
75-79
3.97 (3.18-4.24)
1.14 (0.63-2.05)
2 80
1 1.90 (9.78-14.41)
1.56 (0.72-3.35)
Note. Adapted from EDPRG, 2004b.
L
The primary cause of AMD is still unknown (Prevent Blindness America, 2002) but risk
factors include old age, female sex, white race, cigarette smoking, and low dietary intake of
carotenoids (Gottlieb, 2002). Currently, there is no treatment to prevent or cure AMD but laser
therapy has been shown to delay vision loss in some patients at risk for wet AMD.
Age-Related Cataract (Cataracr)
The lens of the eye is naturally clear but aging, exposure to sunlight, cigarette smoking,
diet or alcohol consumption may lead to the clouding of the lens called age-related cataract
(Prevent Blindness America, 2002). Cataracts can be classified by type, extent, and density
including cortical, posterior sub-capsular, and nuclear (West, 1991). Unlike AMD, a widely
accepted treatment has been found for cataract, which involves removal of the natural lens of the
eye and replacement with an artificial implant (Prevent Blindness America). Medicare spends an
estimated 3.4 billion dollars a year in treating cataract. Cataract extraction is the most common
surgical procedure in the U.S. with more than two million procedures per year ("Nutrition &
Cataracts," n.d.). Although cataract surgery has become quite common, cataract still remains a
primary cause of vision impairment and blindness in those with barriers to accessing appropriate
eye care, especially those in developing countries (West).
Cataract affects about 20.5 million Americans age 40 and older (17.2%) (Prevent
Blindness America, 2002). Prevalence is higher in females (20.0%) than males (13.9%). The
incidence of cataract in Wisconsin is estimated to be 17.9% with 20.9% of females and 14.6% of
males affected. Whites have the highest rate of cataract (18.5%) with Blacks (12.9%), other races
(12.4%), and Hispanics (1 1.7%) following closely behind. Cataract is the main cause of low
vision (excluding blindness) in Whites (59.2%), Blacks (50.9%), and Hispanics (46.7%)
(EDPRG, 2004a). Cataract (36.8%) was the most common cause of blindness in Black
Americans according to the EDPRG (2004a).
As with ANID, the rates of cataract are better understood when data are summarized by
age, gender, and race (See Table 2). In like manner, females have a higher rate of cataract
compared with males of their race. Again, black females have a higher rate of cataract in the
earlier years (age 40 to 69) while white females have a higher rate in the later years (age 70 to 3
80). In contrast, compared to the sharp increase in advanced AMD with age among whites, the
increase is gradual among both races and genders for cataract.
Table 2
Prevalence of cataract by age, gender and race
Rate Der 100 individuals (95% CI)
White Race
Black Race
Gender/Age, years
Females
40-49
50-54
55-59
60-64
65-69
70-74
75-79
2 80
Males
40-49
50-54
55-59
60-64
65-69
70-74
75-79
2 80
71.3 (67.0-75.2)
46.2 (37.9-54.6)
Note. Adapted from EDPRG, 2004c.
In summary, the incidence of AMD and cataract is expected to rise with higher rates
among the Wisconsin population compared to the total U.S. Blindness from AMD and cataract
can affect an individual's physical, social and psychological functioning as described above.
Interestingly, an estimated 50% of all cases of blindness may be preventable (Prevent Blindness
America, 2002). Dietary antioxidants are one possible route of prevention which will be
discussed in the next section. Specifically, the role of lutein and zeaxanthin but also other
carotenoids, vitamins A, C, and E, and zinc in the protection against ARED will be included.
Dietary Intake, Serum Concentrations and Age-related Eye Disease
The Eye Disease Case-Control Study (Seddon, Ajani, et al., 1994) evaluated the
relationship between dietary intake of carotenoids and vitamins A, C, and E and the risk of late
ANID in patients aged 55 to 80 years from five ophthalmology centers in the U.S. Total
carotenoids, total vitamin A, beta-carotene, and lutein and zeaxanthin showed a significant trend
of decreased risk with increasing intake. Lutein and zeaxanthin had the strongest association of
the carotenoids and overall with a statistically significant trend (P <.001) for a reduced risk of
late AMD. Spinach and collard greens were the only carotenoid-rich foods to show a significant
inverse trend with late AMD. An 86% lower risk was found for those who ate five or more
servings of spinach or collard greens (one serving equals 0.5 cups, cooked or raw) per week
compared to those who ate less than one serving per month (OR: 0.14; 95% CI: 0.01, 1.2; P for
trend = <.001).
Two prospective studies compared carotenoid and vitamin A intake with the risk of
cataract extraction in men and women. The intake of U.S. male health professionals aged 45 to
75 years from the Health Professionals Follow-Up Study (Brown et al., 1999) and registered
female nurses aged 45 to 71 years from the Nurses' Health Study (Chasm-Taber et al., 1999)
were evaluated with a semi-quantitative food-frequency questionnaire. In the men, only lutein
and zeaxanthin had a significant trend (P = .03) for decreased risk with increasing intake (Brown
et al.). Men in the highest quintile of lutein and zeaxanthin intake (6.9 mg) had a 19% lower risk
of cataract extraction compared to men in the lowest quintile (1.3 mg) (RR: 0.81; 95% CI: 0.65,
1.01;P for trend = -03). In the women, both lutein and zeaxanthin and vitamin A without
supplements showed a significant trend (P = .04) for decreased risk with increasing intake
although only women at the top decile of lutein and zeaxanthin intake (13.7 mg) had a
significantly decreased risk compared to the bottom quintile (1.2 mg) (RR: 0.78; 95% CI: 0.63,
0.95; P for trend = .04) (Chasm-Taber et al.). Frequent intake (22 times per week) of cooked
spinach was most strongly associated with lower risk with 3 8% lower risk than those with intake
less than 1 time per month (RR: 0.62; 95% CI: 0.45, 0.86; P for trend = .005).
Dietary intake and serum concentrations and AMD have been examined using data from
the National Health and Nutrition Examination Survey (NHANES). Goldberg, Flowerdew,
Smith, Brody, and Tso (1988) compared the consumption of vitamins A and C and the
prevalence of AMD among persons aged 45 to 74 years from the NHANES I. Consumption data
was collected through a 24-hour recall and food frequency questionnaire of fruits and vegetables
rich in vitamins A and C reported as weekly intake over the previous three months. Intake of
h i t s and vegetables rich in vitamin A (OR: 0.57; 95% CI: 0.34,0.96) and rich in vitamin C
(OR: 0.48; 95% CI: 0.27,0.87) four to six times per week from the food frequency data showed
significance for a decreased risk of AMD. After adjustment for demographic and medical
factors, only intake of h i t s and vegetables rich in vitamin A seven or more times per week
remained significant (OR: 0.59; 95% CI: 0.37,0.99).
Mares-Perlman et al. (2001) compared the relationship between lutein and zeaxanthin in
the diet and serum and photographic evidence of early and late AMD in persons aged 40 years
and older from the NHANES 111. Intake data was obtained from a 60-item food frequency
questionnaire. A significantly reduced risk of pigmentary abnormalities (early AMD) was found
in persons aged 40 to 59 years from all races combined (OR: 0.1 ; 95% CI: 0.1,0.3) and NonHispanic Whites (OR: 0.3; 95% CI: 0.1,0.3) in those with the highest versus the lowest quintile
of lutein and zeaxanthin intake in the diet. A significant reduction in late AMD was found in
persons aged 60 to 79 years from all races combined in those with the highest versus the lowest
quintile of lutein and zeaxanthin intake in the diet (OR: 0.1 ;95% CI: 0.0,0.9). The 90th
percentile for lutein and zeaxanthin intake was 5.6 mg in persons aged 40 to 59 years and 6.0 mg
in persons aged 60 to 79 years.
The relationship between serum carotenoids and tocopherols and AMD or cataract was
compared using data from the Beaver Dam Eye Study, a case-control study within a populationbased cohort. Mares-Perlman et al. (1995) investigated the relationship between serum levels and
AMD. No significant differences were found between mean levels of all carotenoids and
tocopherols in persons with or without AMD. While a significantly lower mean level of alphatocopherol was found in persons with AMD than in persons without AMD (P = .03), the
difference was no longer significant after adjusting for serum cholesterol levels. No significant
differences were observed between the highest and lowest quintile of serum carotenoids and
tocopherols and Ah4D. A significantly increased risk was shown in persons in the lowest quintile
of serum lycopene versus all other quintiles combined before (OR: 1.9; 95% CI: 1.O, 3.7) and
after adjustment (OR: 2.2; 95% CI: 1. l , 4.5). Lyle et al. (1999) investigated the relationship
between serum levels and cataract. There was a significant trend of decreased risk of cataract
with increasing levels of serum tocopherol. Persons in the highest versus the lowest tertile of
serum tocopherols showed a significantly reduced risk for cataract (OR: 0.4; 95% CI: 0.2,0.9; P
= .03
for trend).
Antioxidant Supplements and Intake and Age-Related Cataract
The effect of antioxidant supplements on the prevention of age-related cataract has been
studied. Robertson, Donner, and Trevithick (1991) obtained the self-reported intake of vitamin
supplements from the interviews of 304 persons (152 case-control pairs: 59 male, 93 female)
living in southwestern Ontario. The majority (90%) of these participants were aged 60 years or
older. Supplementary vitamin C (OR: 0.30; 95% CI: 0.12,0.75; P = .01) and E (OR: 0.44; 95%
CI: 0.24,0.77; P = .004) intake among participants without cataract was significantly higher than
that of the participants with cataract. These results suggest that supplementary vitamins C and E
may reduce the risk of cataract by 70% and 56%, respectively.
Jacques et al. (1997) invited cataract-free women with the highest and lowest intakes of
vitamin C from the Nurses' Health Study to participate in an investigation of supplement use
over 10 to 12 years before assessment for lens opacities. There were 247 participants aged 56 to
71 years (mean age at eye exam of 62.6 years). Most of the opacities found were early nuclear
(61.1%). Women who took vitamin C supplements for 10 years or longer had a significantly
lower risk of both early (OR: 0.23; 95% CI: 0.09, 0.60) and moderate (OR: 0.17; 95% CI: 0.03,
0.87) opacities at any lens location. No evidence was found for reduced risk from vitamin C
supplement intake for less than 10 years.
Taylor et al. (2002) assessed the total nutrient intake from both food and supplements
among women of the Nurses' Health Study and compared it with age-related cortical and
posterior subcapsular (PSC) opacities from subsequent eye exams. Data were collected from
questionnaires of 492 women aged 53 to 73 years over 13 to 15 years before eye assessment.
Although no significant trends were found between any of the nutrients and either type of
opacities in the overall cohort, a significant association was shown between age and total vitamin
C intake and age and years of vitamin C intake for cortical opacities. A significant inverse trend
was found only among those aged less than 60 years (P for trend .02) for cortical opacities with
increasing vitamin C intake. Those in the highest quintile of vitamin C intake (OR: 0.43; 95%
CI: 0.20,0.93) (364 mg to 2342 mg) had a 57% decreased risk for cortical lens opacities
compared to those in the lowest quintile (140 mg or less). Similarly, a significant inverse trend
was found only among those aged less than 60 years (P for trend .008) for cortical opacities with
increasing duration of vitamin C supplement use. Those who took vitamin C supplements for 10
years or longer (OR: 0.40; 95% CI: 0.18, 0.87) had a 60% decreased risk for cortical lens
opacities compared to those who did not use vitamin C supplements.
The use of vitamin supplements and risk for cataract has been studied among males.
Seddon, Christen, et al. (1994) examined the self-reported intakes of multivitamin, vitamin C,
and/or vitamin E supplements in 17,744 cataract-free males aged 40 to 84 years from the
Physicians' Health Study (PHs). Cataract was assessed by report of the participant in a followup questionnaire and documentation by ophthalmologist in the medical record. The authors did
not find any significant association between use of vitamins C or E and reduced risk of cataract
although these numbers were too small to evaluate. A marginally significant decreased risk of
cataract was found among men who took only a multivitamin supplement (RR: 0.73; 95% CI:
0.54, 0.99; P = .04) compared to men who did not take any vitamin supplements. In addition, a
trend that approached significance (P for trend .06) was found for decreased risk of cataract with
increasing duration of multivitamin use.
Macular Pigment Density
The macula lutea (macula), or yellow spot, of the retina contains the carotenoids lutein
and zeaxanthin (Pratt, 1999). The central-most part of the macula, or the fovea, has the highest
concentration of these yellow pigments (Snodderly, 1995). They are referred to as the macular
pigment (Pratt). Two possible roles of the macular pigment have been suggested: filtering of
damaging blue light from the sun and protection from oxidative damage to lipid membranes of
the eye (Pratt). Low macular pigment density (MPD) may be a risk factor for AMD, cataract and
age-related vision loss. Understanding the factors that influence MPD may assist in the
prevention and treatment of these age-related eye diseases.
MPD and visual sensitivity were assessed and compared between a group of younger
participants (aged 24 to 36 years) and older participants (aged 60 to 84 years) who were nonsmokers and had good ocular health (Hammond, Wooten, & Snodderly, 1998). The older age
group showed a significant positive relationship between MPD and all three measures of visual
sensitivity although no significant relationships were found in the younger subjects. When the
age groups were combined and divided according to their MPD, the group with low MPD had
significantly lower visual sensitivity (in one measure) than those with high MPD. A significant
decrease in MPD was found only in persons older than 60 years. These results suggest that NIPD
may prevent age-related loss of visual function.
Studies have investigated the association of serum concentrations, adipose tissue
concentrations, and dietary intake with MPD. A Netherlands study (Broekrnans et al., 2002)
compared the association between serum lutein and zeaxanthin concentrations and adipose lutein
concentrations on MPD in volunteers aged 18 to 75 years. This study found gender-related
differences, which may explain the higher occurrence of AMD among women. Although serum
lutein and zeaxanthin concentrations (P< .05) and adipose lutein concentrations (P < .001) were
significantly lower in men than in women, mean MPD was 13% higher in men than in women (P
= .02).
An Indianapolis area study (Curran-Celentano et al., 2001) evaluated the serum
concentrations, dietary intake, and MPD in volunteers between ages 18 and 50 years. Dietary
intake was assessed using a one-year food frequency questionnaire. The study found a significant
negative relationship between number of cigarettes smoked per day for current smokers and total
serum carotenoids (r = -.32, P < .005) and serum lutein and zeaxanthin (r = -.26, P < .025). A
significant positive relationship was found between serum lutein (r = .26, P < .0001), serum
zeaxanthin (r = .20, P < .0001), and dietary intake of lutein and zeaxanthin (r = .21, P < .0005)
and MPD.
The relationship of anthropometric measurements to MPD has been investigated
(Hammond, Ciulla, & Snodderly, 2002). Researchers tested the relationship between percent
body fat and body mass index (BMI) and MPD in participants from Athens, Georgia and
Indianapolis (mean age 29.6 years). The average BMI of participants from Athens and
Indianapolis was 24 and 26, respectively. Percent body fat was assessed by bioelectric
impedance and dietary intake was measured using a food frequency questionnaire. A significant
inverse relationship was found between both BMI (r = -.12, P < .0008) and percent body fat (r =
-.12, P < .0 1) and MPD although this relationship was influenced by participants with a high
BMI and percent body fat. No relationship was found when these participants were removed.
Mean MPD was significantly lower in participants with a BMI greater than 29 than those with a
BMI less than 29. Similarly, mean MPD was significantly lower in participants with greater than
27% body fat than those less than 27% body fat. In addition, dietary intake of lutein and
zeaxanthin and total serum carotenoids were significantly lower in high BMI participants (>29).
The authors hypothesized that these differences in MPD may be due to diet and competition with
adipose tissue for lutein and zeaxanthin uptake.
Scientists have attempted to manipulate macular pigment and tissue concentrations
through diet. Hammond, Johnson, et al. (1997) tried to increase MPD through dietary intake of
food sources of lutein and zeaxanthin. Thirteen non-smokers aged 30 to 65 years ate 60 grams of
spinach and 150 grams of corn per day (n = 1O), or ate only the spinach (n = 1) or the corn (n =
2), with a meal andlor fat source in addition to their usual dietary intake for 15 weeks. Those
who responded to the spinach and corn or spinach only (n = 8) had significant increases in MPD
from baseline at weeks 4, 12, and 14 but had a temporary return to baseline at week 8. This is
suggested to reflect interaction with other tissues (i.e. adipose). The responses to corn only
differed with one person showing a considerable increase in serum zeaxanthin (70%) and MPD
(25%) while the other person showed mild increases (6%, 7%) in these measurements,
respectively. Johnson et al. (2000) followed the same dietary protocol of spinach and corn for 15
weeks but also compared the relationships between anthropometric measurements, MPD, and
serum, tissue, and dietary lutein concentrations. Similar to the results of Hammond, Johnson, et
al. (1997), this study found a significant increase in MPD except at week 8. Interestingly, when
MPD decreased at week 8, adipose tissue concentrations increased significantly. These studies
show a possible competition between the adipose and macular tissue for serum carotenoids.
Scientists have investigated the influence of lutein supplementation on MPD. Landrum et
al. (1997) provided 30 mg of free lutein per day to two healthy male volunteers (aged 42 and 5 1)
for 140 days. The supplement, which was taken after breakfast, was natural lutein esters
extracted from marigolds and suspended in 2 ml oil. An increase in MPD started at
approximately days 20 to 40 and continued to increase 40 to 50 days after supplementation
ended. Serum concentrations increased tenfold after 10 to 20 days of supplementation then
dropped to baseline at about 60 days of discontinuing the supplement. The supplementation
produced a 39% and 2 1% mean increase in MPD in the two volunteers, respectively. Similarly,
Berendschot et al. (2000) found a daily lutein supplement significantly increased MPD in eight
nonsmoking volunteers albeit for a shorter length of time (12 weeks) and with a lower dose (10
g). Landrum et al. showed little or no decrease in MPD after the serum concentrations returned to
baseline, which may indicate a slow turnover rate in the retina. The authors suggest that MPD
may reflect carotenoid consumption over an extended length of time. Consistent with this
thought, Hammond, Johnson, et al. (1997) found MPD to remain elevated for several months
after ending a modified diet.
Aging, Antioxidant Concentrations and Age-Related Cataract
The lens is located behind the cornea and iris of the eye and is in contact with the
aqueous humor (Taylor et al., 1995). The youngest tissue is composed of a unicellular layer of
epithelial cells on the anterior surface. These cells divide, differentiate and are compressed
posteriorly into the cortex. The oldest tissue is located in the nucleus of the lens (Yeum, Shang,
Schalch, Russell, & Taylor, 1999). These three layers are surrounded by an outer collagenous
membrane called the capsule (Taylor et al., 1995). The main role of the lens is to collect and
focus light onto the retina. Cataract results when damage due to dehydration and photooxidation
of the lens proteins causes opacification.
The ocular lens is about 98% protein (Taylor et al., 1995). Since these lens cells are
typically not lost with aging, they are at particular risk of harm from light and oxygen. This may
come in the form of ultraviolet light and smoking as well as low concentrations of antioxidant
nutrients. The lens protects itself fiom damage through antioxidant nutrients, antioxidant
enzymes, and proteolytic enzymes. It has been proposed that cataract results from the imbalance
of these protective systems as discussed elsewhere.
Researchers have measured the concentration of antioxidant nutrients in the eye. Yeum,
Taylor, Tang, and Russell (1995) compared the carotenoid, retinoid, and tocopherol
concentrations of normal and cataractous American and cataractous Indian lenses. Lutein and
zeaxanthin were the only carotenoids while retinol, retinyl palmitate, alpha-tocopherol, and
gamma-tocopherol were also found in the human lenses. No differences were found between the
normal and cataractous American lenses. Interestingly, concentrations of lutein, zeaxanthin, and
retinol were significantly higher in the Indian cataractous lenses than both the cataractous and
normal Americans lenses. The authors suggest that other factors also determine cataract risk.
Risk of a type of cataract may be related to the antioxidant concentrations in the layers of
the lens. Yeum et al. (1999) compared the carotenoids, retinol, and tocopherol in the
epithelium/cortex with those in the nucleus. The epithelium/cortex was found to have 3, 1.3, and
1.8 times more lutein and zeaxanthin, retinol, and tocopherol, respectively. Of the total lens, 75%
of lutein and zeaxanthin, 60% of retinol, and 64% of tocopherol were found in the
epitheliudcortex. Even though less exposure to irradiation and oxygen occur in the nucleus,
there is a greater occurrence of this type of cataract. Yeum et al. (1999) have proposed that
greater amounts of these antioxidants in the outer layers of the lens may explain the lower
incidence of these types of cataract.
Increased lens optical density (LOD) is an indicator of an aging lens with cataract being
the end stage. Studies have shown a significant increase in LOD with age (Hammond, Wooten,
& Snodderly, 1997; Berendschot et al., 2002). Hammond, Wooten, et al. (1997) compared the
association between MPD and LOD in younger (aged 24 to 36 years) and older (aged 48 to 82
years) subjects. A significant inverse relationship was found only in the older group (r = -.47, P
< .001). Berendschot et al. (2002) confirmed these results (P
= -.240, P = .005). These studies
give support to lutein and zeaxanthin in the protection from age-related increases in LOD and
cataract (Hammond, Wooten, et al., 1997; Berendschot et al., 2002). Since lutein and zeaxanthin
can not be measured in the lens in vivo, MPD as a biomarker of lens health has shown to be
effective.
Major Clinical Trials
The Age-Related Eye Disease Study (AREDS) was a double-blind, randomized, placebocontrolled clinical trial of 4600 participants in one of four categories of AMD selected from 11
U.S. clinical centers (AREDS Group, 2001a). The AREDS evaluated the effect of high-dose
vitamin C (500 mg), vitamin E (400 IU), beta-carotene (15 mg), zinc (80 mg) and copper (2 mg)
supplements on AMD progression and visual acuity. Participants were randomly assigned to take
daily tablets with: (1) antioxidants, (2) zinc and copper, (3) antioxidants plus zinc or (4) a
placebo. Those not at risk for AMD received only the antioxidants to evaluate the risk of agerelated cataract and visual acuity loss (AREDS Group, 2001b). Zinc (OR: 0.71; 99% C1: 0.52,
0.99) and antioxidants plus zinc (OR: 0.66; 99% CI: 0.47,0.91) significantly reduced the risk of
progression to advanced AMD in persons with intermediate and advanced AMD. But only those
who received antioxidants plus zinc showed a statistically significant reduction in the rate of at
least moderate visual acuity loss (OR: 0.73; 99% CI: 0.54,0.99). Alternatively, no effect of
treatment on the development or progression of age-related cataract or visual acuity loss was
found. The AREDS was the first National Institutes of Health funded study to determine the
effect of high-dose dietary supplements on AMD. Notably, since commercial lutein supplements
were not available at the start of the AREDS, this could not be evaluated (NEI, 2002, July).
The Lutein Antioxidant Supplementation Trial (LAST) was a double-blind, randomized,
placebo-controlled clinical trial of 90 patients with atrophic AMD at two Chicago area veterans
medical facilities (Richer et al., 2004). The aim of the study was to evaluate the effect of lutein
alone or lutein with carotenoids, antioxidants, vitamins and minerals on MPD and measures of
central vision in persons with the most common form of AMD. In comparison, the LAST was
shorter (1 year versus 7 years), had an older mean age (75 years versus 69 years), and had more
male volunteers (95% versus 44%) than the AREDS (Richer et al.; AREDS Group, 2001a).
Patients in the LAST were given: (Group 1) 10 mg lutein, (Group 2) 10 mg lutein combined with
antioxidants, vitamins, and minerals (OcuPower@fiom Nutraceutical Sciences Institute), or
(Group 3) maltodextrin (Richer et al.). Contents of the OcuPower@ supplement given to Group 2
are shown in Table 3. Visual function was assessed using several measures as described
elsewhere. Of these measures, there was an objective improvement in MPD, Snellen visual
acuity, and contrast sensitivity for Groups 1 and 2 while a subjective improvement in the Amsler
grid for Group 1 and glare recovery in Group 2 was found. This is the first trial to show
improvement of several visual functions in patients with AMD (North Chicago VA Medical
Center, 2004). This study supports the effectiveness of lutein combined with antioxidants,
vitamins and minerals in the treatment of AMD although further studies are needed to confirm
this result. In addition, lutein supplementation was found to benefit all stages of AMD (Richer et
al.) as opposed to the AREDS, in which high-dose vitamins and minerals were found to benefit
only moderate to severe stages of AMD (AREDS Group, 2001a).
Table 3
Contents of the OcuPowerB supplement taken during the LAST study
% RDNAI~
Ingredient
Dose
Lutein (FloraGloB)
10 mg
-Vitamin A
2500 IU
83- 108%
15000 IU
-Beta-carotene (BetateneB)
Vitamin C (calcium ascorbate-Ester CB)
1500 mg
1667-2000%
Vitamin D3
400 IU
67-200%
Vitamin E (d-alpha tocopherol succinate)
500 IU
2222%
Vitamin B 1 (thiamin)
50 mg
4167-4545%
Vitamin B2 (riboflavin)
10 mg
769-909%
Vitamin B3 (niacin)
70 mg
438-500%
Vitamin B5 (pantothenic acid)
50 mg
1000%
Vitamin B6
50 mg
2941-3846%
Vitamin B 12
500 mcg
20833%
Folic acid
800 mcg
200%
Biotin
300 mcg
1000%
Calcium
500 mg
42%
Magnesium
300 mg
7 1-94%
Iodine
75 mcg
50%
Zinc (L-methionine-L-OptiZincB)
25 mg
227-3 13%
Copper
1 mg
10%
Manganese
2 mg
87-1 11%
Selenium
200 mcg
36%
Chromium
200 mcg
667- 1000%
Molybdenum
75 mcg
167%
Lycopene
600 mcg
-Bilberry extract (25% anthocyanosides)
160 mg
-Alpha lipoic acid
150 mg
-N-acetyl cysteine
200 mg
-Quercetin
100 mg
-Rutin
100 mg
-Citrus bioflavonoids
250 mg
-Plant enzymes
50 mg
-Black pepper extract (BioperineB)
5 mg
-Malic acid
325 mg
-Taurine
900 mg
-L-glycine
100 mg
-L-glutathione
10 mg
-Boron
2 mg
-Note. See Richer et al., 2004. -- = No RDNAI
aPercent Recommended Daily Allowance/Adequate Intake for females and
males aged 50 years and over.
Lutein and Zeaxanthin: Sources, Bioavailability and Metabolism
Lutein and zeaxanthin can be obtained through foods or supplements. Dark green leafy
vegetables such as kale, collard greens or spinach are the highest dietary sources of lutein and
zeaxanthin while moderate amounts are found in green or yellow vegetables including squash,
peas, broccoli, Brussels sprouts and corn (USDA, n.d.). Lutein first became available to the
supplement market in 1995 in the form of purified, crystalline lutein and zeaxanthin from
marigold flowers (Kreuzer, n.d.). It is now found in hundreds of nutritional supplements (Lutein
Information Bureau, 2006).
Scientists have studied the bioavailability and metabolism of carotenoids from foods and
supplements. Castenmiller, West, Linssen, Hof, and Voragen (1 999) studied the affect of
different levels of processed spinach on the availability of p-carotene and lutein. The study
included a control, carotenoid supplement, whole leaf spinach, minced spinach, liquefied spinach
and liquefied spinach plus dietary fiber group. All groups were fed the same 1-week cycle diet
over a 3-week period. The authors found that processing spinach did not affect the bioavailability
of lutein. The relative bioavailability of lutein was found to be 52% from minced spinach
(Castenmiller et al.) and 67% from a high-vegetable diet (Hof et al., 1999) of the bioavailability
of a lutein supplement added to salad dressing. This shows a lutein supplement is better absorbed
by the body than vegetable-borne lutein.
Lutein may compete with other carotenoids for absorption. Tyssandier et al. (2002) found
competition in chylomicron response to vegetable-borne lutein and lycopene but no effect on
plasma concentration after 3-week supplementation periods. There was a significant increase in
plasma lutein concentrations after 3-week supplementation with chopped spinach, chopped
spinach plus tomato puree, chopped spinach plus lycopene, and lutein plus tomato puree. Burri,
Neidlinger, and Clifford (2002) compared the half-lives of common carotenoids in healthy
women fed a low-carotenoid diet. Lutein was found to have the longest half-life at 76 days while
zeaxanthin had a half-life of 38 days.
Dietary Recommendations and Intake
National organizations have set recommended intakes for fruits and vegetables. One of
the Healthy People 2010 objectives is to eat at least three servings of vegetables daily with at
least one-third being dark green or orange (FDA & NIH, 2000). Only 3% of the population met
this recommendation in 1994-1996. The Dietary Guidelines for Americans recommends eating a
variety of fruits and vegetables daily and to chose from all five vegetable subgroups, including
dark green, several times weekly (USDHHS, 2005). The national 5 A Day for Better Health
Program was started in 1991 as a partnership between the vegetable and fruit industry and the
U.S. government with the goal to increase intake of vegetables and fruits to 5 servings per day
and decrease the incidence of chronic diseases (NCI, 2001).
Currently, no recommended level of lutein and zeaxanthin intake has been proposed (The
National Academy of Sciences, 2000) although the Eye Disease Case Control Study and analysis
of the Third National Health and Nutrition Examination Survey found 5.8 mg (Seddon, Ajani, et
al., 1994) and 6 mg (Mares-Perlman et al., 2001) per day, respectively reduced the risk of AMD.
Analysis of the Nurses' Health Study and Health Professionals Follow-Up Study showed 6 mg
(Chasm-Taber et al., 1999) and 6.9 mg (Brown et al., 1999) per day, respectively reduced the
need for cataract surgery. The LAST study demonstrated 10 mg lutein per day improved visual
function in persons with atrophic AMD (Richer et al., 2004).
Although several studies have shown a relationship between diets high in lutein and
zeaxanthin and eye health, consumption remains low (CDC, 2006). The Behavioral Risk Factor
Surveillance System telephone health survey found that in 2005, only 23.2% of adults
nationwide and 22.2% of adults in Wisconsin consumed fruits and vegetables five or more times
per day. The 50th percentile for lutein and zeaxanthin intake varies according to study
population. The Beaver Dam Eye Study showed a 0.9 mg per day intake (Mares-Perlman et al.,
1995) while the Eye Disease Case Control Study found a 1.7 mg per day intake (Seddon, Ajani,
et al., 1994).
Safety and Use of Dietary Supplements
The safety of taking lutein and other nutritional supplements for age-related cataract and
macular degeneration has been questioned (Sperduto, Ferris, & Kurinjj, 1990; Mares-Perlman,
1999). In 1990, Sperduto et al. advised caution in the recommendation of supplements for agerelated macular degeneration and cataract due to unknown efficacy and undefined toxicity levels
for many nutrients. In 1999, Mares-Perlman warned that enthusiastically recommending lutein
supplements for cataract before a strong body of scientific evidence is established would damage
the credibility of science in the public eye and may cause adverse outcomes as was the case with
p-carotene and lung cancer. The National Eye Institute (NEI) released a statement in July 2002
explaining that claims supporting the role of lutein supplements in decreasing the risk of AMD
or cataract were still speculative. Richer, the LAST lead investigator, makes clear in a North
Chicago VA Medical Center (2004) statement that studies are needed of increased population
and length of time on the treatment of AMD with lutein and antioxidant supplements. On the
other hand, a recent study conducted by The Lewin Group (2006) for the Dietary Supplement
Education Alliance estimated a five-year $2.5 million net savings through avoiding dependency
associated with risk of AMD by taking 6-10 mg of lutein with zeaxanthin daily. Clearly,
researchers differ in their perceptions of the appropriateness of lutein, zeaxanthin, and
antioxidants for eye health.
Despite the lack of evidence regarding the long-term safety and efficacy of lutein in the
prevention and treatment of AMD and cataract, it has become the most used herbal and other
natural dietary supplement (Kelly et al., 2005). The main source of lutein supplementation was
from a multivitamin product. The National Marketing Institute's survey (November 20,2003)
found 61.2% of Americans were aware of lutein, 29.2% said it was important for their stores to
carry foods and beverages enriched with lutein, and 77.1% said they were concerned with
preventing vision problems (as cited in Kemin Industries, Inc., 2006). The results of these
surveys show the need for optometrists and other eye healthcare professionals to stay informed
of the research on lutein and eye health and to provide credible recommendations and
educational materials that consider the current body of evidence.
Optometry and Nutrition Education
Optometrists are uniquely positioned to promote the intake of a healthy diet including
dark green vegetables for optimal eye health. They may also provide credible information to
guide patients on the use of nutritional supplements. The American Optometric Association's
Clinical Practice Guidelines advises optometrists that evidence is increasing to support
nutritional supplementation for eye health but that further research is needed to define those
therapies (AOA, 1999). Eating five or more servings of dark green leafy vegetables per week is
suggested to reduce risk for AMD. Dietary supplementation with vitamins C and E, betacarotene and selenium is recommended for nutrient-deficient or noncompliant adults although
optometrists are advised to consult with the patient's primary care physician before
recommending nutritional supplements. Referring a patient to a registered dietitian may assist
concerned optometrists in determining current dietary intake, the appropriateness of nutritional
supplementation, or nutrition education for eye health.
Chapter 111: Methodology
Introduction
The purpose of this study was to describe how the confidence of licensed Wisconsin
optometrists in the relationship between diets high in lutein and zeaxanthin and eye health
influenced their clinical practice as measured by a self-administered survey. This chapter will
review subject selection and description, instrumentation, data collection, data analysis and
limitations.
Subject Selection and Description
A complete listing of 794 licensed Wisconsin optometrists was obtained from the
Wisconsin Department of Regulations and Licensing. After assigning a three digit number to all
optometrists excluding those who pre-tested the survey, a random sample of 300 optometrists
was selected using a table of random digits. A letter of consent was mailed to the sample of
optometrists requesting their participation in the study (Appendix A). The letter specified the
objectives of the study, the subjects' rights as study participants, and that returning the survey
indicated their agreement to participate. Since the study instrument was designed for currently
practicing optometrists, the letter asked that only currently practicing optometrists participate. A
pre-addressed, pre-paid envelope was included for return of the survey instrument. The surveys
were not coded or marked with an identification number, and did not have any personal
identifiers therefore the sample was anonymous.
Instrumentation
A 20-item original survey was developed after a thorough review of epidemiological,
prospective, and clinical studies on lutein and zeaxanthin found in nutrition, eye, and medical
journals. Two locally practicing optometrists and one other practicing optometrist agreed to pre-
test the survey for errors and to improve the quality. Modifications in survey length and content
were made based upon the pre-test. A copy of the survey is located in Appendix B. Since the role
of lutein and zeaxanthin in eye health is still under investigation, it was the aim of this study to
gather the opinions and recommendations of the most frequently sought providers of eye care,
optometrists. The items in the survey were divided into four main sections.
The first section addressed Wisconsin optometrists' awareness of lutein and zeaxanthin,
sources of information on lutein and zeaxanthin, and perception of the adequacy of the
information on lutein and zeaxanthin. The first item was a 5-point scale measuring the
awareness of optometrists on the relationship between lutein and zeaxanthin and eye health. The
next two items were concerning the sources of information on the relationship between lutein
and zeaxanthin and eye health. The first of the two items asked respondents to mark all of their
sources of information while the second asked respondents to rank their top three most preferred
sources of information. The last item in this section asked whether the information on lutein and
zeaxanthin was adequate to make recommendations to patients.
The second section asked respondents to mark which of the following foods or
supplements they recommended to patients: (1) foods rich in lutein and zeaxanthin, (2) a lutein
or zeaxanthin supplement, (3) a vitamin A or beta-carotene supplement, (4) a vitamin C
supplement, (5) a vitamin E supplement, (6) a zinc supplement, or a (7) multi-vitaminlmineral
supplement. Patients were divided into five categories: (1) patients not at risk of AMD or
cataract, (2) patients at risk of AMD, (3) patients at risk of cataract, (4) patients diagnosed with
AMD, and ( 5 ) patients diagnosed with cataract. A follow-up question was placed after the item
addressing the recommendation of a vitamin A or beta-carotene supplement. Respondents who
recommended a vitamin A or beta-carotene supplement were asked if they recommended it to
patients who smoked.
The third section referred to the educational or informational materials the optometrist
distributed to patients. The first question asked if the optometrist distributed educational or
informational materials to patients at hisher practice. If the optometrist distributed educational
or informational materials, the next question was whether helshe had educational or
informational materials on lutein and zeaxanthin. If the optometrist had educational or
informational materials on lutein and zeaxanthin, the next item asked the respondent to mark all
the places where educational or informational materials on lutein and zeaxanthin were obtained.
If the optometrist did not distribute educational or informational materials to patients at hisher
practice or did not have educational or informational materials on lutein and zeaxanthin, the
respondent was asked to rank hisher top three reasons for not distributing educational or
informational materials on lutein and zeaxanthin. The last question in this section used a 7-point
scale to determine the importance to the optometrist of having educational or informational
materials on lutein and zeaxanthin to give to patients.
The fourth section of the survey included three demographic questions and a comment
section. The first question asked for the gender of the optometrist. The next question asked the
number of years the respondent had been practicing optometry (rounded to the closest year). The
last question asked the age of the optometrist. The survey concluded by asking respondents to
comment if they felt that there was something missing from the survey regarding the topic of
lutein and zeaxanthin and eye health.
Data Collection Procedures
Permission from the Institutional Review Board of the University of Wisconsin-Stout
was granted before data collection began. This research project was partially funded through an
award from the University of Wisconsin-Stout Student Research Fund. The letter of consent and
the 20-item survey was sent on May 19,2003 with a requested response date of June 2,2003.
Postcards were sent on May 30,2003 to remind optometrists to complete and return the survey
with the date extended to June 13,2003 (Appendix C). In addition, a reminder to return the
survey was published in the June issue of the Wisconsin Optometric Association's monthly
newsletter.
Data Analysis
This study was descriptive in design. The majority of survey items were nominal
variables. The researcher coded the survey variables then entered and analyzed the data using
The Statistical Program for Social Sciences (SPSS) version 11.5 for Windows. Data were
analyzed for descriptive statistics including frequency, percentage, mode, median, range of
scores, mean, and standard deviation. Cross-tabulations were calculated to describe the data
more fblly.
Limitations
The present study was limited in the sample size, research population, and survey design.
The sample selected to receive the mailed survey represented only 38% of the total population of
licensed Wisconsin optometrists. The research sample was selected from the total population of
licensed Wisconsin optometrists. Therefore, inferences from the results should not be applied to
optometrists nation-wide or ophthalmologists, who also provide eye care to patients. Data were
collected via an original survey instrument. Since this survey was designed for this study, there
are no measures of validity or reliability.
Chapter IV: Results
Introduction
The purpose of this study was to determine the perceptions, recommendations, and
educational materials of licensed Wisconsin optometrists regarding the relationship between
lutein and zeaxanthin and eye health. A 20-item survey was mailed to 300 randomly chosen
licensed Wisconsin optometrists. This chapter will describe demographic information, item
analysis, selected item response by gender, response analysis within items, and research
objectives.
Demographic Information
A one-page survey was sent to 300 optometrists on May 19,2003, which was followed
by a reminder postcard 1 1 days later. A total of 128 surveys were returned. Of those surveys, 127
were completed and one survey was returned because the address had changed and forwarding
time had expired. Similarly, two postcards were returned due to the same reason. Two
optometrists who reported that they only received the postcard contacted the researcher by phone
to request another survey, which was resent. Therefore, it is estimated that 297 optometrists
received both the survey and reminder postcard. The response rate was 42.3%. This represented
16.0% of the total population of licensed optometrists in Wisconsin at that time.
The fourth section of the survey included three demographic items, which will be
discussed here. The first item in this section (n = 127) asked "What is your gender?" Ninety-five
(74.8%) of the participants were male and 3 1 (24.4%) were female.
Table 4 presents the response to the question "How many years have you been practicing
optometry?" Respondents were asked to round to the closest year. The number of years
practicing optometry ranged from two years to 45 years. The mean and median number of years
practicing optometry were 16.9 years and 17.0 years, respectively. There was a standard
deviation of 9.6 years. The data were bimodal with 20 years and 23 years being tied (6.3%) as
the most fiequently reported number of years practicing optometry. Five years and 11 years were
tied (5.5%) as the second most fiequently reported number of years practicing optometry.
Table 4
How many years have you been practicing
optometry? (round to closest year) (n =
127)
YO
Years
n
45 to 49
1
0.8
Note. Respondents wrote in their years
practicing. Responses have been grouped.
Table 5 presents the response to the question "What is your age?'The mean and median
ages of the optometrists were 43.6 years and 43.5 years, respectively. There was a standard
deviation of 9.1 years. Ages ranged from 28 years to 70 years. The most frequently reported age
of the optometrists was 44 years (6.3%) with 37 years, 39 years, and 55 years tied for second
Table 5
What is your age? (n = 127)
Years
n
YO
Note. Respondents wrote in their ages
in years. Responses have been grouped.
Item Analysis
This portion of the chapter will provide an analysis of the data from the first three
sections of the survey which include information on lutein and zeaxanthin and eye health,
nutritional recommendations to patients, and educational or informational materials distributed to
patients. Data from the fourth section of the survey were described above except for a request for
comments at the conclusion of the survey, which said
We are interested in your perceptions of lutein and zeaxanthin and eye health. If you feel
that there is something missing from this survey that should have been asked to practicing
optometrists regarding the topic of lutein and zeaxanthin and eye health, please comment
below.
These comments are included in Appendix D. Statistics will be limited to frequencies and
percentages as the data are nominal and ordinal. After each item is described, cross-tabulations
between items will be utilized to provide more detail about responses within selected items.
Information on Lutein and Zeaxanthin and Eye Health
The first section of the survey included four items. Table 6 presents the results to the
question "How informed do you feel about the relationship between lutein and zeaxanthin and
eye health?" No (n = 0) optometrists were uniformed, 20 (15.7%) were somewhat informed, 53
(4 1.7%) were moderately informed, 45 (35.4%) were very informed, and 7 (5.5%) were
extremely informed. The majority (n = 98,77.2%) of optometrists were moderately to very
informed about the relationship between lutein and zeaxanthin and eye health.
Table 6
How informed do you feel about the relationship
between lutein and zeaxanthin and eye health?
(check one) (n = 127)
Res~onse
n
%
0
0.0
Uninformed
Somewhat informed
20
15.7
Moderately informed
53
41.7
45
35.4
Very informed
Extremely Informed
7
5.5
Table 7 shows the response to the question "Where have you obtained information on the
relationship between lutein and zeaxanthin and eye health?" Respondents were asked to check all
that applied. Optometrists obtained information from the following: 27 (2 1.3%) from the TV,
newspaper, radio, 22 (17.3%) from the Internet, 55 (43.3%) from colleagues, 63 (49.6%) from
pharmaceutical companies or representatives, 114 (89.8%) from studies published in professional
journals, 102 (80.3%) from materials published by professional organizations or obtained at
professional meetings, 30 (23.6%) from the National Eye Institute, 25 (19.7%) from non-profit
organizations dedicated to preventing age-related eye disease, and 7 (5.5%) from other sources.
These other sources were continuing education (n = 3,2.4%), a lecture (n = 2, 1.6%), the
Physician's Desk Reference for Nutritional Supplements (n = 1,0.8%), and PubMed (n = 1,
0.8%). The top three obtained sources of information on the relationship between lutein and
zeaxanthin and eye health were: (1) studies published in professional journals, (2) materials
published by professional organizations or obtained at professional meetings, and (3)
pharmaceutical companies or representatives.
Table 7
Where have you obtained information on the relationship between lutein
and zeaxanthin and eye health? (check all that apply) (n 127)
%
Response
n
TV, newspaper, radio
27
2 1.3
Internet
Colleagues
Pharmaceutical companies or
representatives
Studies published in professional
114
journals
Materials published by professional
102
organizations or obtained at
professional meetings
National Eye Institute (NEI)
30
Non-profit organizations dedicated to
25
preventing age-related eye disease
Other
7
--
Table 8 shows the results to "Using a scale of 1 to 3, please rank your top 3 most
preferred sources of information on lutein and zeaxanthin and eye health." Eighty-three (65.4%)
preferred studies published in professional journals, 24 (18.9%) preferred materials published by
professional organizations or obtained at professional meetings, and 5 (3.9%) preferred .the
National Eye Institute as their most preferred source of information on lutein and zeaxanthin and
eye health. Sixty-three (49.6%) preferred materials published by professional organizations or
obtained at professional meetings, 24 (18.9%) preferred studies in professional journals, and 9
(7.1%) preferred the National Eye Institute as their second most preferred source of information
on lutein and zeaxanthin and eye health. Thirty-two (25.2%) preferred pharmaceutical companies
or representatives, 22 (17.3%) preferred colleagues, and 21 (16.5%) preferred the National Eye
Institute as their third most preferred source of information on lutein and zeaxanthin and eye
health. Continuing education (n = 4,3.1%) and an educational lecture or course (n = 1,0.8%)
were preferred sources of information on lutein and zeaxanthin and eye health in the "other"
category. The most fiequently preferred sources of information on lutein and zeaxanthin and eye
health were: (1) studies published in professional journals (n = 113, 89.0%), (2) materials
published by professional organizations or obtained at professional meetings (n = 107, 84.2%),
and (3) pharmaceutical companies or representatives (n = 42,33.1%). It appears that optometrists
have obtained information fiom their preferred sources.
Table 8
Using a scale of 1 to 3, please rank your top 3 most preferred sources of
information on lutein and zeaxanthin and eye health. (n = 127)
Res~onse
Rank
n
%
TV, newspaper, radio
Internet
Colleagues
Pharmaceutical companies or
representatives
Studies published in professional
journals
Materials published by professional
organizations or obtained at
professional meetings
National Eye Institute (NEI)
Non-profit organizations dedicated
to preventing age-related eye disease
Other: Continuing education
Other: Educational lecture or course
The next item asked "Is the information on lutein and zeaxanthin and eye health adequate
for you to make recommendations to patients?Ninety-nine (78.0%) indicated the information
on lutein and zeaxanthin and eye health was adequate, 16 (12.6%) indicated the information was
not adequate while 12 (9.4%) indicated they were not sure if the information was adequate for
them to make recommendations to patients.
Nutritional Recommendations to Patients
The second section of the survey included eight items. For each of the eight items,
respondents were given six options. These included "patients not at risk of AMD or cataract,"
"patients at risk of AMD," "patients at risk of cataract," "patients diagnosed with AMD," or
"patients diagnosed with cataract." If the optometrist did not recommend the foods or
supplement, an option was given that said "I have not recommended [the foods or supplement] to
patients." Item number eight was an exception, which asked "If you recommend a vitamin A or
beta-carotene supplement to patients, do you recommend it to patients who smoke?"
of these data are shown in Table 9 by subgroup.
summary
Table 9
NAR
n
Response
Spinach
("4
RAMD
n
("A)
Subgroup
RC
n
(%I
DAMD
n
("4
DC
n
("A)
10 1
19
99
20
16
(12.6)
(78.0)
(15.7)
(79.5)
(15.0)
Lutein
7
96
10
103
13
(5.5)
(75.6)
(7.9)
(8 1.1)
( 1 0.2)
85
18
15
Vitamin A
11
72
(66.9)
(14.2)
(1
1.8)
(56.7)
(8.7)
27
58
28
Vitamin C
14
49
(21.3)
(45.7)
(22.0)
( 1 1 .O)
(38.6)
66
17
57
18
Vitamin E
16
(44.9)
(14.2)
(52.0)
(13.4)
(12.6)
85
8
10 1
9
Zinc
9
(6.3)
(7.1)
(79.5)
(7.1)
(66.9)
Multi-vitamin
40
100
44
100
42
(3 1.5)
(78.7)
(34.6)
(78.7)
(33.1)
Note. NAR = not at risk of AMD or cataract; RAMD = at risk of AMD; RC = at
risk of cataract; DAMD = diagnosed with AMD; DC = diagnosed with cataract.
The first item in this section said "I recommend spinach or other foods rich in lutein and
zeaxanthin to." Table 10 presents the data as respondents who recommended the foods or
supplements to any patients. One hundred-nine (85.8%) recommended and 18 (14.2%) had not
recommended spinach or foods rich in lutein and zeaxanthin to patients. Most respondents
recommended spinach or other foods rich in lutein and zeaxanthin to those at risk ( n = 99,
78.0%) or those diagnosed ( n = 101,79.5%) with AMD.
The next item said "I recommend a lutein or zeaxanthin supplement to." One hundred-ten
(86.6%) recommended and 16 (12.6%) had not recommended a lutein or zeaxanthin supplement
to patients. Most respondents recommended a lutein or zeaxanthin supplement to those at risk ( n
= 96,
75.6%) or those diagnosed ( n = 103,8 1.1 %) with AMD.
The next item said "I recommend a vitamin A or beta-carotene supplement to." Ninetyfive (74.8%) recommended and 32 (25.2%) had not recommended a vitamin A or beta-carotene
supplement to patients. Most respondents recommended a vitamin A or beta-carotene
supplement to those at risk ( n = 72,56.7%) or those diagnosed (n = 85,66.9%) with AMD.
The next item asked "If you recommend a vitamin A or beta-carotene supplement to
patients, do you recommend it to patients who smoke?" Of those who recommended a vitamin A
or beta-carotene supplement ( n = 95),25 (26.3%) recommended and 66 (69.5%) had not
recommended a vitamin A or beta-carotene supplement to patients who smoke.
The next item said "I recommend a vitamin C supplement to." Seventy-five (59.1%)
recommended and 52 (40.9%) had not recommended a vitamin C supplement to patients. Less
than half of respondents recommended a vitamin C supplement to those at risk ( n = 49,38.6%)
or those diagnosed ( n = 58,45.7%) with AMD.
The next item said "I recommend a vitamin E supplement to." Seventy-four (58.3%)
recommended and 52 (40.9%) had not recommended a vitamin E supplement to patients. Less
than half of respondents recommended a vitamin E supplement to those at risk of AMD ( n = 57,
44.9%) while more than half recommended it to those diagnosed with AMD ( n = 66,52.0%).
The next item said "I recommend a zinc supplement to." One hundred-eight (85.0%)
recommended and 19 ( 1 5%) had not recommended a zinc supplement to patients. Most
respondents recommended a zinc supplement to those at risk ( n = 85,66.9%) or those diagnosed
( n = 101,79.5%) with AMD.
The last item said "I recommend a multi-vitamidmineral supplement to." One hundredsixteen (91.3%) recommended and 1 1 (8.7%) had not recommended a multi-vitaminlmineral
supplement to patients. Most respondents recommended a multi-vitamidmineral supplement to
those at risk (n = 100, 78.7%) or those diagnosed (n = 100, 78.7%) with AMD. A multivitamidmineral supplement was the most recommended foods or supplement to those not at risk
of AMD or cataract. The most recommended foods or supplements were a multi-vitamidmineral
supplement (n = 1 16,91.3%), a lutein or zeaxanthin supplement (n = 1 10, 86.6%), spinach or
foods rich in lutein or zeaxanthin (n = 109, 85.8%), and a zinc supplement (n = 108, 85%).
Table 10
I recommend [foods or supplements] to [any] patients (n =
127)
Response
n
'YO
Spinach or other foods
Yes
109
85.8
No
18
14.2
Lutein or zeaxanthin
Yes
110
86.6
No
16
12.6
Vitamin A or beta-carotene
Yes
No
Vitamin C
Yes
No
Vitamin E
Yes
No
Zinc
Yes
No
Multi-vitamidmineral
Yes
116
91.3
No
11
8.7
Educational or Informational Materials Distributed to Patients
The third section of the survey included five items. The first item in this section asked
"Do you currently distribute educational or informational materials to patients at your practice?"
One hundred-one (79.5%) currently distributed and 25 (19.7%) did not currently distribute
educational or informational materials to patients at their practice in MayIJune of 2003.
The next item asked "Do you have educational or informational materials on lutein and
zeaxanthin?" Of those who were distributing educational or informational materials (n = 10l), 5 1
(50.5%) had educational or informational materials and 50 (49.5%) did not have educational or
informational materials on lutein and zeaxanthin.
Table 11 presents the results to the question "Where have you obtained your educational
or informational materials on lutein and zeaxanthin?" Optometrists obtained materials from the
following: 26 (5 1.0%) from the American Optometric Association, 18 (35.3%) from the National
Eye Institute, 10 (19.6%) from the American Academy of Ophthalmology, 12 (23.5%) from the
American Macular Degeneration Foundation, 7 (13.7%) from the Alliance for Aging Research,
24 (47.1%) from pharmaceutical companies, 12 (23.5%) developed their own, and 11 (21.6%)
from other sources. These other sources were 1 (2.0%) from an ophthalmology newsletter, 1
(2.0%) from an article by an M.D., 3 (5.9%) from a Journal, 1 (2.0%) from commercially
available patient pamphlets, 1 (2.0%) from another optometrist, 1 (2.0%) from Research to
Prevent Blindness, 1 (2.0%) from PubMed, 1 (2.0%) from the American Academy of Optometry,
and 1 (2.0%) from an ophthalmology group. The most frequently obtained sources of educational
or informational materials on lutein and zeaxanthin were (I) the American Optometric
Association, (2) pharmaceutical companies, and (3) the National Eye Institute.
Table 11
Where have you obtained your educational or informational
materials on lutein and zeaxanthin? (check all that apply) (n =
51)
Response
n
YO
American Optometric Association
26
51.0
National Eye Institute (NEI)
18
35.3
American Academy of
10
19.6
Ophthalmology
American Macular Degeneration
12
23.5
Foundation
Alliance for Aging Research
7
13.7
Pharmaceutical companies
24
47.1
I develop my own
12
23.5
Other
11
21.6
Table 12 shows the results to "If you currently do not distribute educational or
informational materials on lutein and zeaxanthin, using a scale of 1 to 3, please rank your top 3
reasons for not distributing educational or informational materials on lutein and zeaxanthin."
Thirty-one (41.3%) marked "unsure of where to obtain," 18 (24.0%) marked "I would rather
answer questions directly," and 17 (22.7%) marked "research is limited" as their most important
reason for not distributing educational or informational materials on lutein and zeaxanthin.
Twelve marked "time to obtain, develop, or reproduce" (1 6.4%), 12 marked "I would rather
answer questions directly" (16.0%), and 10 (13.3%) marked "research is limited as the second
most important reason for not distributing educational or information materials on lutein and
zeaxanthin. Ten (13.7%) marked "time to obtain, develop, or reproduce," 9 (12.2%) marked
"cost to obtain, develop, or reproduce," and 7 each marked "unsure of where to obtain" (9.3%)
and "research is limited" (9.3%) as the third most important reason for not distributing
educational or informational materials on lutein and zeaxanthin. The most frequent reasons for
not distributing educational or informational materials on lutein and zeaxanthin were: (1) "unsure
of where to obtain" (n = 43, 57.3%), (2) "I would rather answer questions directly" (n = 35,
46.7%), (3) "research is limited" (n = 34,45.3%), and (4) "time to obtain, develop, or reproduce"
(n = 27,37.0%). One respondent (1.3%) each specified the following four "other" reasons for not
distributing educational or informational materials on lutein and zeaxanthin: an unspecified other
reason, "lutein and zeaxanthin is included with other topic in my handout," "would like to have
samples," and "misinformation is being passed around.. ." It should be noted that several
respondents who had materials on lutein and zeaxanthin responded to this item. These responses
were included in this item's total because these respondents may not be distributing the materials
on lutein and zeaxanthin to patients.
Table 12
If you currently do not distribute educational or informational materials on lutein
and zeaxanthin, using a scale of 1 to 3, please rank your top 3 reasons for not
distributing educational or informational materials on lutein and zeaxanthin.
n
940
Response
Rank
Unsure of where to obtainC
1
31
41.3
I would rather answer questions
directlyC
Not my responsibilityd
No patient interestd
Cost to obtain, develop, or reproduceb
Time to obtain, develop, or reproducea
Research is limitedC
Available materials either have too
small print or are above the reading
level of my patientsd
Other: unspecifiedb
Other: Lutein and zeaxanthin is
included with other topic in my
handoutd
Other: Would like to have samplesd
Other: Misinformation is being passed
aroundd
Table 13 listed the results to "How important is it to you to have educational or
informational materials on lutein and zeaxanthin to give to your patients?'The following
responses were received: 14 (1 1.0%) marked extremely important, 32 (25.2%) marked very
important, 50 (39.4%) marked somewhat important, 22 (17.3%) marked undecided, 4 (3.1%)
marked somewhat unimportant, 3 (2.4%) marked very unimportant and no one marked extremely
unimportant. It was somewhat to very important for the majority of optometrists (n = 82,64.6%)
to have educational or informational materials on lutein and zeaxanthin to give to their patients.
Table 13
How important is it to you to have educational or
informational materials on lutein and zeaxanthin to give
to your patients? (n = 127)
Response
Extremely important
Very important
Somewhat important
Undecided
Somewhat unimportant
Very unimportant
Extremely unimportant
32
50
22
4
3
0
25.2
39.4
17.3
3.1
2.4
0.0
Selected Item Response by Gender
Gender of the optometrist was cross-tabulated with selected survey items to compare
responses between genders. From a total of 124 respondents (94 male, 30 female), females felt
slightly more informed than males about the relationship between lutein and zeaxanthin and eye
health (Table 14). Eighty percent (n = 24) of females were moderately to very informed
compared to 77.6% (n
women (n
= 3,
=
73) of males. Men (n
=
17, 18.1%) were more somewhat informed than
10.0%) while women (n = 3, 10.0%) were more extremely informed than men (n
Table 14
How informed do you feel about the relationship between lutein and zeaxanthin and
eye health? within gender (n = 124)
Res~onse
Gender
Uninformed Somewhat Moderately
Very
Extremely
Male
35
4
0
17
38
n
0.0
18.1
40.4
37.2
4.3
% within
Female
0
3
14
10
3
n
33.3
10.0
0.0
10.0
46.7
% within
From a total of 126 respondents (95 male, 3 1 female), a higher percentage of females (n =
27, 87.1%) than males (n = 72, 75.8%) thought the information on lutein and zeaxanthin and eye
health was adequate for them to make recommendations to patients (Table 15). Both genders
were similar in the percentage of those who were not sure if the information was adequate
(males: n = 9, 9.5%; females: n = 3,9.7%).
Table 15
Is the information on lutein and zeaxanthin and eye health
adequate for you to make recommendations to patients? within
gender (n = 126)
Response
Gender
Yes
No
Not sure
Male
n
72
14
9
% within
75.8
14.7
9.5
Female
n
27
1
3
% within
87.1
3.2
9.7
From a total of 125 to 126 respondents (53 to 85 male, 17 to 30 female), most of the
supplements were recommended at a higher percentage by females than males (Table 16).
Females recommended spinach or other foods rich in lutein and zeaxanthin (males: n = 8 1,
85.3%; females: n = 28,90.3%), a vitamin A or beta-carotene supplement (males: n = 70,73.7%;
females: n = 25, 80.6%), a vitamin C supplement (males: n = 53, 55.8%; females: n = 22,
71.0%), and a multi-vitaminlmineral supplement (males: n = 85, 89.5%; females: n = 30,96.8%)
at a higher percentage than males. Men recommended a vitamin E supplement (males: n = 57,
60.6%; females: n = 17, 54.8%) and a zinc supplement (males: n = 83, 87.4%; females: n = 25,
80.6%) at a higher percentage than females. Recommendation of a lutein or zeaxanthin
supplement was similar between genders (males: n = 83, 88.3%; females: n = 27, 87.1%).
Table 16
I recommend [foods or supplements] to patients within gender
Response
Vitamin Vitamin Vitamin
Gender
%inachb Luteina
cb
Ea
Male
70
53
57
n
81
83
85.3
88.3
73.7
55.8
60.6
% within
Female
28
27
25
22
17
n
90.3
87.1
80.6
71.O
% within
54.8
a n = 125. n = 126.
zincb
Multivitb
83
87.4
85
89.5
25
80.6
30
96.8
In contrast to the gender results from the first three cross-tabulations, there is a larger
difference in gender response when respondents were asked about having or the importance of
having educational or informational materials to give to patients. From a total of 126 respondents
(95 male, 3 1 female), a higher percentage of females (n = 30,96.8%) than males (n = 71,74.7%)
currently distributed educational or informational materials to patients at their practice in
MayIJune 2003 (Table 17). Of those that distributed educational or informational materials (n =
101), a higher percentage of males (n = 42,59.2%) than females (n = 9,30.0%) had educational
or informational materials on lutein and zeaxanthin (Table 18).
Table 17
Do you currently distribute educational or
informational materials to patients at your
practice? within gender (n = 126)
Response
Gender
Yes
No
Male
n
71
% within
74.7
Female
n
30
% within
96.8
Table 18
Do you have educational or informational
materials on lutein and zeaxanthin? within
gender (n = 101)
Response
Gender
Yes
No
Male
42
29
n
% within
59.2
40.8
Female
9
21
n
% within
30.0
70.0
From a total of 125 respondents (94 male, 3 1 female), it was more important to females
than males to have educational or informational materials on lutein and zeaxanthin to give to
their patients (Table 19). It was somewhat to very important to 7 1.O% (n = 22) of females
compared to 63.8% (n = 60) of males. Only men thought it was unimportant to have educational
or informational materials on lutein and zeaxanthin to give to their patients: somewhat to very
unimportant to 7.4% (n = 7).
Table 19
How important is it to you to have educational or informational materials on lutein and
V
)
Res~onse
Important
Male
n
Unimportant
% within
10
10.6
26
27.7
34
36.2
17
18.1
4
4.3
3
3.2
0
0.0
Female
n
% within
4
12.9
6
19.4
16
51.6
5
16.1
0
0.0
0
0.0
0
0.0
Response Analysis within Items
Where respondents obtained information on the relationship between lutein and
zeaxanthin and eye health (item number two) was compared with how informed respondents felt
about the relationship between lutein and zeaxanthin and eye health (item number one). The data
are presented in Table 20. Those who obtained information from the internet had the highest
percentage of extremely informed respondents (n = 5,22.7%) compared to those who obtained
information elsewhere. Those who obtained information from the National Eye Institute had the
highest percentage of very informed respondents (n = 15,51.7%) compared to those who
obtained information elsewhere. Those who obtained information from colleagues had the
highest percentage of moderately informed respondents (n = 25,46.3%) compared to those who
obtained information elsewhere. And those who obtained information from the TV, newspaper,
radio had the highest percentage of somewhat informed respondents (n = 6,23.1%) compared to
those who obtained information elsewhere. None of these results include the "other" category
due to limited response.
Table 20
How informed do you feel about the relationship between lutein and
zeaxanthin and eye health? within Where have you obtained information
on the relationshin between lutein and zeaxanthin and eve health?
Response to how informed
Response to
obtained
Uninformed Somewhat Moderately Very Extremely
0
6
11
7
2
n
26.9
7.7
0.0
23.1
42.3
% within
Internet
n
% within
Colleagues
n
% within
Pharm
n
% within
Studies
n
% within
Materials
n
% within
NEI
n
% within
Non-profit
n
% within
Lecture
n
% within
CPE
n
% within
PDR
n
% within
PubMed
n
% within
Note. TV = TV, newspaper, radio; Pharm = pharmaceutical companies or
representatives; Studies = studies published in professional journals;
Materials = materials published by professional organizations or obtained
Table 20 Continued
at professional meetings; NEI = National Eye Institute; Non-profit = nonprofit organizations dedicated to preventing age-related eye disease; CPE
= continuing education; PDR = physicians desk reference for nutritional
supplements.
The perceived adequacy of the information on lutein and zeaxanthin and eye health to
make recommendations to patients (item number four) was compared with how informed
respondents felt about the relationship between lutein and zeaxanthin and eye health (item
number one). Results are found in Table 2 1. The majority of optometrists who thought the
information was adequate to make recommendations to patients (n = 97) were moderately to very
informed (n = 82, 84.5%) while the majority of those who thought the information was not
adequate (n = 16) were somewhat to moderately informed (n = 15,93.7%).
Table 2 1
How informed do you feel about the relationship between lutein and
zeaxanthin and eye health? within Is the information on lutein and
zeaxanthin and eye health adequate for you to make recommendations to
patients? (n = 125)
Response to
Response to how informed
adequate
Uninformed Somewhat Moderately Very Extremely
Yes
0
8
41
7
n
41
% within
0.0
8.2
42.3
42.3
7.2
No
n
0
8
7
1
0
0.0
50.0
% within
43.8
6.3
0.0
Not sure
n
0
4
5
3
0
% within
0.0
33.3
41.7
25.0
0.0
The recommendations of optometrists for spinach or other foods rich in lutein and
zeaxanthin (item number five) and for a lutein or zeaxanthin supplement (item number six) were
compared with the perceived adequacy of the information on lutein and zeaxanthin and eye
health to make recommendations to patients (item number four). The results are shown in Tables
22 and 23. Those who recommended spinach or other foods rich in lutein and zeaxanthin to
patients (n = 109) were more likely (n = 88, 80.7%) to indicate the information on lutein and
zeaxanthin and eye health was adequate to make recommendations compared to those who did
not recommend spinach (n = 11 , 61.1%). Those who did not recommend a lutein or zeaxanthin
supplement were more likely to indicate the information on lutein and zeaxanthin and eye health
was not adequate to make recommendations to patients (n = 10,62.5%) compared to those who
did recommend a lutein or zeaxanthin supplement (n = 6, 5.5%).
Table 22
Is the information on lutein and zeaxanthin and eye health
adequate for you to make recommendations to patients?
within I recommend spinach or other foods rich in lutein
and zeaxanthin to ~atients
Response to
Response to adequate
recommend
Not
s~inach
Yes
No
sure
Yes
n
88
9
12
8.3
11.0
% within
80.7
No
11
7
0
n
% within
61.1
38.9
0.0
Table 23
Is the information on lutein and zeaxanthin and eye health
adequate for you to make recommendations to patients?
within I recommend a lutein or zeaxanthin supplement to
patients (n = 126)
Response to
Response to adequate
recommend
Not
lutein
Yes
No
sure
Yes
n
94
6
10
% within
85.5
5.5
9.1
No
n
4
10
2
% within
25.0
62.5
12.5
Respondents who recommended foods or supplements to patients (item number five to
12) was cross-tabulated with whether respondents recommended these foods or supplements to
patients at risk or diagnosed with AMD (Table 24). Of those that recommend the foods or
supplements in the survey, a majority recommended each of these to patients at risk or diagnosed
with AMD.
Table 24
Patients at risk or diagnosed with AMD within I recommend [foods or
supplements] to patients
Response
At Risk of
Diagnosed with
AMD
Response to
AMD
Yes
No
recommend
Yes
No
Spinacha
n
% within
~utein~
n
% within
Vitamin AC
n
% within
Vitamin cd
n
% within
Vitamin Ee
n
% within
zincf
n
% within
Multi-vitaming
n
% within
The recommendations of optometrists for spinach or other foods rich in lutein and
zeaxanthin (item number five) and for a lutein or zeaxanthin supplement (item number six) was
compared with whether optometrists had educational or informational materials on lutein and
zeaxanthin (item number 14). Tables 25 and 26 present the results. A slightly higher percentage
of optometrists who recommended spinach to patients (n = 90) had educational or informational
materials on lutein and zeaxanthin (n = 46, 5 1.1%) compared to those who did not recommend (n
=
1 1) spinach or other foods rich in lutein and zeaxanthin to patients (n = 5,45.5%). On the other
hand, optometrists who recommended a lutein or zeaxanthin supplement (n = 89) were
noticeably more likely to have educational or informational materials on lutein and zeaxanthin (n
= 48,53.9%)
compared to those who do not recommend (n = 11) a lutein or zeaxanthin
supplement to patients (n = 2, 18.2%).
Table 25
Do you have educational or informational
materials on lutein and zeaxanthin? within I
recommend spinach or other foods rich in lutein
and zeaxanthin to patients (n = 101)
Response to
Response to materials on lutein
recommend
spinach
Yes
No
Yes
n
46
44
% within
51.1
48.9
No
n
5
6
% within
45.5
54.5
Table 26
Do you have educational or informational
materials on lutein and zeaxanthin? within I
recommend a lutein or zeaxanthin supplement
to
-patients (n = 100)
Response to
Response to materials on lutein
recommend
lutein
Yes
No
Yes
n
48
41
% within
53.9
46.1
No
n
2
9
% within
18.2
8 1.8
Perceived adequacy of the information on lutein and zeaxanthin and eye health to make
recommendations to patients (item number four) was compared with whether optometrists had
educational or informational materials on lutein and zeaxanthin (item number 14). Data are
shown in Table 27. From a total of 101 respondents (83 yes, 9 no, 9 not sure), optometrists who
thought the information was adequate were more likely (n = 46,55.4%) to have educational or
informational materials on lutein and zeaxanthin than those who did not think the information
was adequate (n = 1, 11.1%). Those who were not sure if the information on lutein and
zeaxanthin was adequate were slightly more likely to not have educational or informational
materials on lutein and zeaxanthin (n = 5, 55.6%) than those who thought the information was
adequate (n = 37,44.6%).
Table 27
Do you have educational or informational
materials on lutein and zeaxanthin? within Is the
information on lutein and zeaxanthin and eye
health adequate for you to make
recommendations to patients? (n = 101)
Response to
Response to materials
adeauate
Yes
No
Yes
37
n
46
% within
55.4
44.6
No
1
8
n
% within
11.1
88.9
Not sure
n
4
5
% within
44.4
55.6
Whether optometrists had educational or informational materials on lutein and zeaxanthin
(item number 14) was compared with the importance of having educational or informational
materials on lutein and zeaxanthin (item number 17). See Table 28 for results. From a total of
100 respondents (50 yes, 50 no), it was somewhat to extremely important to have educational or
informational materials on lutein and zeaxanthin for the majority of optometrists who had
materials on lutein and zeaxanthin (n = 48,96.0%) while it was undecided to very important to
have materials on lutein and zeaxanthin for most of the optometrists who did not have materials
on lutein and zeaxanthin (n = 47,94.0%).
Table 28
How important is it to you to have educational or informational materials on lutein and
zeaxanthin to give to your patients? within Do you have educational or informational
materials on lutein and zeaxanthin? (n = 100)
Response to
Response to how important
materials
Extremely Very Somewhat Undecided Somewhat Very
on lutein
Yes
15
2
0
0
19
14
n
4.0
0.0
0.0
38.0
30.0
% within
28.0
No
12
1
2
0
12
23
n
24.0
2.0
4.0
0.0
24.0
46.0
% within
Research Objectives
Research Objective #1: Evaluate the awareness, sources of information, and confidence
of Wisconsin optometrists on the relationship between diets high in lutein and zeaxanthin
and eye health.
The first section of the survey, which included item number one through four, addressed
research objective # l . The majority (n = 98, 77.2%) of optometrists were moderately to very
informed about the relationship between lutein and zeaxanthin and eye health (Table 6). The top
three obtained sources of information on the relationship between lutein and zeaxanthin and eye
health were: (1) studies published in professional journals (n = 114, 89.8%), (2) materials
published by professional organizations or obtained at professional meetings (n = 102, 80.3%),
and (3) pharmaceutical companies or representatives (n = 63,49.6%) (Table 7). The most
frequently preferred sources of information on lutein and zeaxanthin and eye health were: (1)
studies published in professional journals (n = 113, 89.0%), (2) materials published by
professional organizations or obtained at professional meetings (n = 107, 84.2%), and (3)
pharmaceutical companies or representatives (n = 42, 33.1%) (Table 8). The majority of
optometrists (n = 99, 78.0%) indicated the information on lutein and zeaxanthin and eye health
was adequate for them to make recommendations to patients.
Research Objective #2: Determine the nutritional recommendations of Wisconsin
optometrists for the prevention or treatment of AMD and cataract.
The second section of the survey, which included item number five through 12, focused
on research objective #2. The following foods or supplements were recommended by
optometrists in descending order: a multi-vitamidmineral supplement (n = 116,91.3%), a lutein
or zeaxanthin supplement (n = 110, 86.6%), spinach or other foods rich in lutein and zeaxanthin
(n = 109, 85.8%), a zinc supplement (n = 108, 85.0%), a vitamin A or beta-carotene supplement
(n = 95,74.8%), a vitamin C supplement (n = 75,59.1%), and a vitamin E supplement (n = 74,
58.3%) (Table 10). More than half of respondents recommended all foods or supplements in the
survey except a vitamin C or vitamin E supplement to those at risk of AMD and except a vitamin
C supplement to those diagnosed with AMD (Table 9). None of the foods or supplements in the
survey were recommended by a majority of the optometrists to those not at risk of AMD or
cataract, those at risk of cataract, or those diagnosed with cataract although about one-third of
optometrists recommended a multi-vitamidmineral supplement to these groups.
Research Objective #3: Assess the availability and importance of educational materials
on lutein and zeaxanthin to Wisconsin optometrists.
The third section of the survey, which included item number 13 through17, investigated
research objective #3. Most optometrists were distributing educational or informational materials
to patients at their practice (n = 101,79.5%) although about half (n = 51,50.5%) of those who
were distributing materials had educational or informational materials on lutein and zeaxanthin.
The most frequently obtained sources of educational or informational materials on lutein and
zeaxanthin were (1) the American Optometric Association, (2) pharmaceutical companies, and
(3) the National Eye Institute (Table 11). The most frequent reasons for not distributing
educational or informational materials on lutein and zeaxanthin were: (1) "unsure of where to
obtain" (n = 43, 57.3%), (2) "I would rather answer questions directly" (n = 35,46.7%), (3)
"research is limited" (n = 34,45.3%), and (4) "time to obtain, develop, or reproduce" (n = 27,
37.0%) (Table 12). It was somewhat to very important for the majority of optometrists (n = 82,
64.6%) to have educational or informational materials on lutein and zeaxanthin to give to their
patients (Table 13).
Research Objective #4: Summarize the perceptions of Wisconsin optometrists of lutein
and zeaxanthin and eye health.
A request for comments located below item number 20 allowed respondents to write their
perceptions of lutein and zeaxanthin and eye health or the survey itself (See Appendix D). A few
respondents suggested questions they would ask other optometrists while many of the
respondents explained why they recommend or do not recommend lutein and zeaxanthin
supplements or made reference to the age-related eye disease study (AREDS).
Research Objective #5: Describe the demographic characteristics of Wisconsin
optometrists.
The fourth section of the survey, which included item number 18 through 20, looked into
research objective #5. Approximately three-fourths (74.8%) of the optometrists were men. The
mean age of the optometrists was about 43 years (43.6 years). The youngest respondent was 28
years while the oldest was 70 years. The mean number of years practicing optometry for the
respondents was almost 17 years (16.9 years). The responding optometrists had been practicing
from two to 45 years.
Chapter V: Discussion
Introduction
The purpose of this study was to determine how the perceptions of licensed Wisconsin
optometrists toward lutein and zeaxanthin and eye health affected their current practice. This
section will include a discussion of the results, limitations, conclusions and recommendations for
optometrists, patients and further study.
Discussion
Evidence is accumulating regarding the role of lutein and zeaxanthin in age-related eye
disease (Mares-Perlman et al., 2002). Although the evidence is still preliminary as to support the
use of spinach as a functional food for prevention and lutein and zeaxanthin supplements for the
treatment of age-related eye disease, the consumption of spinach (Lucier, Allshouse, & Lin,
2004) and the popularity of lutein supplements has risen (Kelly et al., 2005). As with any
emerging therapy, it is important for health professionals to remain objective in their evaluation
of potential treatments for disease and provide accurate, evidence-based advice to patients.
This study investigated the sources of information licensed Wisconsin optometrists
obtained on the relationship between lutein and zeaxanthin and eye health. Our results showed
studies published in professional journals, materials published by professional organizations or
obtained at professional meetings, pharmaceutical companies or representatives, colleagues, and
the National Eye Institute to be the top five sources of information on the relationship between
lutein and zeaxanthin and eye health. The National Eye Institute's National Eye Health
Education Program (NEHEP) Low Vision Focus Groups Final Report found similar results (NEI,
2004). Journal articles, continuing education classes, professional conferences, the internet, and
conversations with colleagues were the most frequent responses to materials that
ophthalmologists and optometrists use to educate themselves.
The present study was not the first of its kind. After our study data were collected and
analyzed, an internet search found a survey commissioned by Kemin Foods (Des Moines, Iowa),
manufacturer of FloraGLOB brand lutein, that assessed the level of awareness, acceptance of
and commitment to lutein in 150 randomly chosen ophthalmologists and 150 randomly chosen
optometrists in the United States (Young Again Nutrients, 2002; HighBeam Research, Inc.,
2002). The study was conducted by Jefferson Davis Associates, an independent research firm in
Cedar Rapids, Iowa, in June and July 200 1.
Our study found about 86% of optometrists currently recommended spinach or other
foods rich in lutein and zeaxanthin to their patients. This was slightly below the results of the
Kemin Foods survey (Young Again Nutrients, 2002) in which 90% of ophthalmologists and
optometrists believed consumers should eat foods naturally high in lutein such as spinach. Our
study showed about 87% of optometrists recommended a lutein or zeaxanthin supplement to
patients. Eighty-four percent of ophthalmologists and optometrists in the Kernin Foods survey
(Young Again Nutrients) currently recommended lutein to their patients, which is slightly below
our results. The most recommended nutritional supplement in our study was a multivitamidmineral supplement (91% of optometrists). This result supports the recommendation of
Fletcher and Fairfield (2002) for all adults to take one multivitamin daily. In our study, of those
that recommended a multi-vitamidmineral supplement, about 86% (86.2%) recommended it to
those at risk or diagnosed with age-related macular degeneration (AMD). In contrast, while this
survey did not ask if optometrists recommended a multi-vitamidmineral supplement with lutein,
the Kemin Foods survey (Young Again Nutrients) found 86% of ophthalmologists and
optometrists believed consumers who take a multivitamin should take one that includes lutein. It
is unknown which subgroups the Kemin Foods respondents recommended a multivitamin with
lutein for.
We were interested in the educational or informational materials optometrists distributed
to patients, particularly those on lutein and zeaxanthin. The most common sources of these
materials were obtained from the American Optometric Association, pharmaceutical companies,
the National Eye Institute, the American Macular Degeneration Foundation, and from
developing their own. Although the NEHEP report (NEI, 2004) found more general sources,
these sources appear to be consistent with our results. The most frequent materials NEHEP
ophthalmologists and optometrists currently used to educate patients included journal articles,
continuing education classes, pamphlets and brochures, videos, the internet, and professional
conferences.
Limitations
This study was limited in the sample, population, and study design. First, the research
sample was limited in size and by possible bias. The response rate was good although this
represented only 16% of the total population of licensed Wisconsin optometrists. Optometrists
who chose to respond to the survey may feel more strongly about the relationship between lutein
and zeaxanthin and eye health than those who did not respond. Second, the study population was
limited to the currently licensed optometrists in Wisconsin. Therefore, inferences from the results
should only be applied to licensed Wisconsin optometrists rather than licensed optometrists in
other states or nationwide or to ophthalmologists in Wisconsin, other states or nationwide. Third,
data collection was via an original survey instrument. Since the survey was designed for this
study, there are no measures of validity or reliability. At the time of data collection, the Age-
Related Eye Disease Study (AREDS) was a major eye study in which optometrists were likely to
base their nutritional recommendations. Our survey asked optometrists about their
recommendations for these vitamins and minerals but each was asked separately. The most
recommended supplement was a multi-vitamidmineral supplement. While the AREDS
formulation was a multi-vitamidmineral supplement, it is not known what percentage of
optometrists recommended this specific supplement to patients.
Conclusions
The objectives of this study were met. The first objective was to evaluate the awareness,
sources of information, and confidence of Wisconsin optometrists on the relationship between
diets high in lutein and zeaxanthin and eye health. The majority of respondents were moderately
to very informed about the relationship between lutein and zeaxanthin and eye health (77.2%).
Those who obtained information from the internet had the highest percentage of extremely
informed respondents (22.7%) compared to those who obtained information elsewhere. The top
three obtained sources of information on the relationship between lutein and zeaxanthin and eye
health were also the top three most preferred sources of information on lutein and zeaxanthin and
eye health. The majority of optometrists thought the information on lutein and zeaxanthin and
eye health was adequate for them to make recommendations to patients (78.0%). This percentage
was higher among female (87.1%) than male (75.8%) respondents. Most optometrists who
thought the information was adequate were moderately to very informed (84.5%) while those
who did not think the information was adequate were somewhat to moderately informed
(93.7%). These results suggest that the more information optometrists obtained, the more likely
they were to find that the information on lutein and zeaxanthin and eye health was adequate to
make recommendations to patients.
The second objective was to determine the nutritional recommendations of Wisconsin
optometrists for the prevention or treatment of AMD and cataract. The majority of respondents
recommended all foods or supplements listed in the survey except a vitamin C supplement to
patients diagnosed with AMD and except a vitamin C or vitamin E supplement to patients at risk
of AMD. When those who recommended each of the supplements was cross-tabulated with
patients at risk or diagnosed with AMD, a majority of the respondents recommended all of these
supplements to patients. None of the foods or supplements in the survey were recommended by a
majority of the optometrists to patients at risk of cataract or patients diagnosed with cataract. It is
concluded that most optometrists recommended a multi-vitamidmineral supplement to patients
at risk or diagnosed with AMD although what formulations and for which stages of AMD are
unknown.
The third objective was to assess the availability and importance of educational materials
on lutein and zeaxanthin to Wisconsin optometrists. The majority of optometrists were
distributing educational or informational materials to patients at their practice (79.5%). Of the
respondents who distributed these materials, about half had educational or informational
materials on lutein and zeaxanthin (50.5%). Although a higher percentage of female (96.8%)
respondents distributed educational or informational materials than males (74.7%), this was
reversed for materials on lutein and zeaxanthin (males: 59.2%, females: 30.0%). Optometrists
obtained their educational or informational materials on lutein and zeaxanthin from a variety of
sources, the most common being the American Optometric Association (5 1.0%), pharmaceutical
companies (47.1%), and the National Eye Institute (35.3%). Of those who did not distribute
educational or informational materials on lutein and zeaxanthin, most respondents were unsure
of where to obtain these materials (57.3%). It was somewhat to very important for the majority
of optometrists (64.6%) to have educational or informational materials on lutein and zeaxanthin
to give to their patients. This percentage was higher among females (71.0%) than males (63.8%).
Twenty-eight percent of the optometrists who already had educational or informational materials
on lutein and zeaxanthin thought it was extremely important to have educational or informational
materials on lutein and zeaxanthin to give to patients compared to none of the optometrists who
did not have educational or informational materials on lutein and zeaxanthin. This implies that
optometrists will seek out patient materials on lutein and zeaxanthin if it is important to them.
Recommendations
While it is encouraging that none of the respondents in our study were uninformed about
the relationship between lutein and zeaxanthin and eye health, a modest amount were only
somewhat informed (15.7%). When results of the less informed (somewhat and moderately) and
more informed (very and extremely) respondents were split between two groups, there was a
majority of less informed (57.5%) compared to the more informed (40.9%) respondents. This
supports the need for optometrists to become more informed of the current state of literature on
lutein and zeaxanthin and eye health. Future research should focus on the reason optometrists
were less informed so appropriate educational strategies can be developed.
It was found that respondents who obtained information from the internet (22.7%), the
National Eye Institute (20.7%), and non-profit organizations dedicated to preventing age-related
eye disease had the highest percentage of respondents who were extremely informed. These
results suggest that optometrists found these to be the most effective sources for obtaining
information on the relationship between lutein and zeaxanthin and eye health.
It was interesting to find differences in the availability and importance of educational or
informational materials on lutein and zeaxanthin among male and female respondents. Although
a higher percentage of women (96.8%) had educational or informational materials than men
(74.7%), men (59.2%) had a higher percentage of educational or informational materials on
lutein and zeaxanthin than women (30.0%). A higher percentage of women (83.9%) thought it
was somewhat to extremely important to have educational or informational materials on lutein
and zeaxanthin to give to patients compared to men (74.5%) while a higher percentage of men
(7.4%) thought it was somewhat to very unimportant compared to women (0%). Gender was
cross-tabulated with two options from item 16 that asked respondents to rank their top three
reasons for not distributing materials on lutein and zeaxanthin (i.e. unsure of where to obtain, I
would rather answer questions directly). It is intriguing to note that 30.9% of men (n = 17) while
only 5.0% of women (n = 1) ranked "I would rather answer questions directly" as their most
important reason for not distributing educational or informational materials on lutein and
zeaxanthin. In addition, 57.9% of women (n = 11) and 35.7% of men (n = 20) ranked "unsure of
where to obtain" as their most important reason for not distributing educational or informational
materials on lutein and zeaxanthin.
In summary, it appears that although a higher percentage of women had educational
materials and thought it was more important to have these materials than men, a higher
percentage of women did not know where to obtain these. On the other hand, it looks as if men
were less likely to have educational or informational materials because it was less important to
them (although had a higher percentage of materials on lutein and zeaxanthin) and they would
rather instruct patients verbally. This shows a need for organizations to publicize the availability
of educational or informational materials to optometrists as a majority of female optometrists
were unsure of where to obtain these materials. Men may have had more materials on lutein and
zeaxanthin because they knew where to obtain these. Optometrists may also find it helpful to
stay connected to services of professional, governmental, and non-profit organizations to
improve their current practice. In addition, patients may benefit from having an optometrist who
provides information in a format conducive to their learning preference.
In conclusion, this survey attempted to measure several aspects of how lutein and
zeaxanthin affected the practice of licensed Wisconsin optometrists. Future research should focus
on increasing sample size, including ophthalmologists and modifying the survey to include items
that address barriers to obtaining information on nutrition for eye health, recommendations for
specific formulations of nutritional supplements, and frequency of referrals to a dietitian. It
would also be interesting to do a follow-up survey to compare responses from the original to at
least five years post-study.
As research accumulates on the influence of nutrition in the prevention of age-related eye
disease, it is anticipated that there will be an increased demand from patients and insurers to
provide nutrition education to improve patient outcomes. With the lack of financial incentive for
optometrists to provide this type of education, patient educational materials or a referral to a
dietitian may be key strategies in improving the ocular and overall health of the patient.
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Appendix A: Cover Letter
May 19,2003
Dear Dr.
9
I am a graduate student at the University of Wisconsin-Stout and am interested in the relationship
between diets high in lutein and zeaxanthin and eye health including the prevention of age-related
macular degeneration (AMD) and cataract. For my research study in Food and Nutritional Sciences, I
have chosen to send a survey to optometrists in Wisconsin regarding this topic. The objectives of my
research are: (1) to evaluate the awareness and sources of information of Wisconsin optometrists on the
relationship between lutein and zeaxanthin and eye health; (2) to determine the nutritional
recommendations of Wisconsin optometrists for age-related eye disease; and (3) to assess the availability
of educational materials on lutein and zeaxanthin to Wisconsin optometrists. Enclosed is a simple, 20question survey for you to fill out and return in the self-addressed stamped envelope by June 2, 2003.
There are no personal identifying questions that will allow me as the researcher to connect your returned
survey with you as an individual optometrist. Please note that this survey was designed for currently
practicing optometrists. Therefore, if you are not currently practicing, please disregard our request.
It is understood that by returning this survey, you are giving your informed consent as a participating
volunteer in this study. The potential risks to you as a practicing optometrist participating in this study
are minimal. The potential benefits that might be realized from the successful completion of this study
are an increased knowledge of Wisconsin optometrists' sources of information on lutein and zeaxanthin,
their nutritional recommendations for age-related eye disease, and their availability of educational
materials on lutein and zeaxanthin. The information is being sought in a specific manner so that your
anonymity is guaranteed. You have the right to refuse to participate by not returning the survey.
Questions or concerns about the research study should be addressed to Tara Larson, the researcher, phone
(507) 436-5448, or Janice Coker, the research advisor, phone (715) 232-2239. Questions about the rights
of research subjects can be addressed to Sue Foxwell, Human Protections Administrator, UW-Stout
Institutional Review Board for the Protection of Human Subjects in Research, 11 Harvey Hall,
Menomonie, WI 5475 1, phone (715) 232-1 126.
Your participation in this study is very important to us. Please know that we appreciate your time and are
requesting your response by June 2,2003.
Sincerely,
Tara A. Larson
Graduate Student
Department of Food and Nutrition
University of Wisconsin-Stout
Appendix B: Survey Instrument
Note: Original survey was one page, printed on both sides of 8.5 inch x 14 inch paper, and
organized into four columns.
Please return this survey by June 2,2003 in the pre-addressed postagepaid envelope provided.
Thank you
Department of Food and Nutrition
c/o Tara Larson, graduate student
University of Wisconsin-Stout
Menomonie, WI 54751-0790
Email: larsonta~uwstout.edu
Several recent studies have indicated a relationship between diets high in lutein and zeaxanthin and eye
health including the prevention of agerelated macular degeneration (AMD) and cataract.
1. How informed do you feel about the relationship between lutein and zeaxanthin and eye health? (check
one)
Uninformed
- Somewhat informed
- Moderately informed
- Very informed
Extremely informed
2.
Where have you obtained information on the relationship between lutein and zeaxanthin and eye health?
(check all that apply)
lV, newspaper, radio
lnternet
Colleagues
Pharmaceutical companies or representatives
Studies published in professional journals
Materials published by professional organizations or obtained at professional meetings
National Eye Institute (NEI)
Non-profit organizations dedicated to preventing agerelated eye disease
Other (please specify)
3.
-
~p
-
I haven't obtained any information.
Using a scale of 1to 3, please RANK YOUR TOP 3 MOST PREFERRED SOURCES of information on lutein
and zeaxanthin and eye health.
-
lV, newspaper, radio
Internet
Colleagues
Pharmaceutical companies or representatives
Studies published in professional journals
Materials published by professional organizations or obtained at professional meetings
National Eye Institute (NEI)
Non-profit organizations dedicated to preventing agerelated eye disease
Other (please specify)
4.
Is the information on lutein and zeaxanthin and eye health adequate for you to make recommendations
to patients? (check one)
-
Yes
No
Not sure
We are interested in your current nutritional recommendations to patients. Please check which patients you
recommend the following foods or supplements to. (check all that apply)
5.
1 recommend spinach or other foods rich in lutein and zeaxanthin to
-
-
Patients NOT at risk of AMD or cataract
Patients at risk of AMD
Patients at risk of cataract
Patients diagnosed with AMD
Patients diagnosed with cataract
I have not recommended spinach or other foods rich in lutein and zeaxanthin to patients.
6. 1 recommend a lutein or zeaxanthin supplement to
7.
1 recommend a vitamin A or betacarotene supplement to
8.
Patients NOT at risk of AMD or cataract
Patients at risk of AMD
Patients at risk of cataract
Patients diagnosed with AMD
Patients diagnosed with cataract
I have not recommended a lutein or zeaxanthin supplement to patients.
Patients NOT at risk of AMD or cataract
Patients at risk of AMD
Patients at risk of cataract
Patients diagnosed with AMD
Patients diagnosed with cataract
I have not recommended a vitamin A or betacarotene supplement to patients.
If you recommend a vitamin A or betacarotene supplement to patients, do you recommend it to patients
who smoke?
Yes
No
9.
1 recommend a vitamin C supplement to
-
Patients NOT at risk of AMD or cataract
Patients at risk of AMD
Patients at risk of cataract
Patients diagnosed with AMD
Patients diagnosed with cataract
I have not recommended a vitamin C supplement to patients.
10.1 recommend a vitamin E supplement to
-
-
-
Patients NOT at risk of AMD or cataract
Patients at risk of AMD
Patients at risk of cataract
Patients diagnosed with AMD
Patients diagnosed with cataract
I have not recommended a vitamin Esupplement to patients.
11.I recommend a zinc supplement to
-
-
Patients NOT at risk of AMD or cataract
Patients at risk of AMD
Patients at risk of cataract
Patients diagnosed with AMD
Patients diagnosed with cataract
I have not recommended a zinc supplement to patients.
12.1 recommend a multi-vitamin/mineraI supplement to
-
-
Patients NOT at risk of AMD or cataract
Patients at risk of AMD
Patients at risk of cataract
Patients diagnosed with AMD
Patients diagnosed with cataract
I have not recommended a multi-vitamin/mineraI supplement to patients.
We are interested in the educational or informational materials you distribute to patients.
13. Do you currently distribute educational or informational materials to patients at your practice? (check
one)
Yes
No (skip next 2 questions)
14. Do you have educational or informational materials ON LUTEIN AND ZEAXANTHIN? (check one)
Yes
No (skip next question)
15.Where have you obtained your educational or informational materials ON LUTEIN AND ZEAXANTHIN?
(check all that apply)
-
American Optometric Association
National Eye Institute (NEI)
American Academy of Ophthalmology
American Macular Degeneration Foundation
Alliance for Aging Research
Pharmaceutical companies
Idevelop my own
Other (please specify)
16. IF YOU CURRENTLY DO NOT DISTRIBUTE educational or informational materials ON LUTEIN AND
ZEAXANTHIN, using a scale of 1to 3, please RANK YOUR TOP 3 REASONS for NOT distributing
educational or informational materials on lutein and zeaxanthin.
-
Unsure of where to obtain
Iwould rather answer questions directly
Not my responsibility
No patient interest
Cost to obtain, develop, or reproduce
Time to obtain, develop, or reproduce
Research is limited
Available materials either have too small print or are above the reading level of my patients
Other (please specify)
17. How important is it to you to have educational or informational materials ON LUTEIN AND ZEAXANTHIN
to give to your patients? (check one)
-
-
Extremely important
Very important
Somewhat important
Undecided
Somewhat unimportant
Very unimportant
Extremely unimportant
We would like to ask you some demographic questions to better describe the optometrists in our study.
18. What is your gendefl
Male
Female
19. How many years have you been practicing optometry? (round to closest year)
20. What is your age?
We are interested in your perceptions of lutein and zeaxanthin and eye health. If you feel that there is
something missing from this survey that should have been asked to practicing optometrists regarding the
topic of lutein and zeaxanthin and eye health, please comment below.
Thank you for your participation in our study.
Appendix C: Reminder Postcard
Dear optometrist,
We would like to remind you to complete the survey on lutein and zeaxanthin and eye health we
sent you by mail and return it in the postage-paid envelope provided. If you have already
returned your completed survey, we would like to thank you for your participation. If you have
not yet completed the survey, we have extended our requested date of return to June 13,
2003. We hope this will allow you sufficient time to answer our simple 20-question survey. We
look forward to receiving your answers. If you are not currently practicing optometry, please
disregard our reminder.
If you have any questions or concerns, please contact us at (507) 436-5448, Tara Larson,
researcher, or (715) 232-2239, Janice Coker, research advisor.
Appendix D: Comments from Respondents
We are interested in your perceptions of lutein and zeaxanthin and eye health. If you feel that
there is something missing from this survey that should have been asked to practicing
optometrists regarding the topic of lutein and zeaxanthin and eye health, please comment below.
Note: Comments were transcribed as closely to original as possible. Therefore, misspelled words
were included.
I feel it is better safe than sorry - if there is a chance of them working against ARM use
them.
I have read a lot regarding lutein but very little on zeaxanthin - would be interesting to know
if others felt the same - I answered all questions based on my experience with lutein. Perhaps you should separate the two.
The main reason I don't recommend luteidzeaxanthin is that it was not included in the
AREDS (Age Related Eye Disease Study) Study. As I obtain study results confirming the
benefits of luteidzeaxanthin, I would be more willing to recommend it.
I give information to my ARMD patients on the AREDS study and discuss the added
probable benefit of lutein & zeaxanthidgreen leafy veg. I don't at this point have material
that I distribute with the lutein & zeaxanthin info on it.
How often do patients specifically ask about lutein & zeaxanthin (Pt interest)
I think there is not enough scientific data to know for sure if these are helpful for AMD. They
have not shown to 1 incidence of cataract. More research needs to be done.
You should have asked about recommendations for the specific supplements used in the
AREDS study, which DID show clear benefit to some people with AMD.
Thank you for taking the time and your interest in this area of study. I eagerly await the
results of your survey.
Unfortunately the studies to determine the effectiveness of lutein & zeaxanthin are very small
samples and not of long duration like the Age Related Eye Disease Study (AREDS) was to
show effectiveness of antioxidants and zinclcopper supplements. Doseage amounts and other
factors are only determined for now on very weak study results and mostly set by supplement
manufacturers. Therefore to recommend a supplement to a patient for the carotenoids is only
done on a "we think it may be beneficial" basis. Quoting PDR for Nutritional Supplements
"...show some promise of protecting against macular degeneration and may reduce the risk
of cataract in some. Not exactly the confidence level one needs to prescribe these
supplements with the assurance you can alter the course of a disease.
Ask the questions: what information should be lor would you like to see1 on the pamphlets
given out to your patients.
Not aware of double blind studies like ARED study of ocuvite.
Do you see studies have shown a solid relationship between lutein & zeaxanthin and see
progression (not development) of macular degeneration?
Unless I'm mistaken, it sounds like this study is being paid for by a pharmaceutical company.
I think it is important to stress (1) A good diet with Fresh fruits and vegetables. (2) Moderate
exercise (3) No smoking. Although supplements are good they give a false impression. A
healthy Lifestyle will do more in most cases than taking high dose supplements.
I am not aware of any studies conducted on these, other than those funded by pharmaceutical
companies.
Good luck on your study. My good friend did much of the original research on this subject at
the University of Houston. He's a univ of
-grad circa 1971, career Army. Dr.
Morris Lattimoie not sure of his result or where this info. may have been published. I saw
parts in numerous journal studies in 1990's.
I do not feel that the evidence for lutein and zeaxanthin, zinc, B-carotene, Vit E and Vit C are
conclusive. The cause of age related macular degeneration of both the wet and dry forms are
obscure and appear to have relationships to UV exposure, ethnicity (especially fair skin),
nutrition, smoking and as yet unidentified factors. Having said this, a nutritional andor
supplemental approaches are relatively inexpense, probably cause no harm and may be
proven to help with macular degeneration. Therefore, I usually recommend the use of
supplements, eg, Ocuvite, to those patients presenting with drusen, macular pigmentary
changes and early dry age related macular degeneration There also comes a time, eg,
geographic atrophy, when nutritional approaches are too late.
As optometrists counsel patients on the use of supplements, they must also inform patients of
the cost of such products as Ocuvite. A monthly supply is approximately $20 = $240/yr
which is a large amount for low income seniors. High intake of green leafy vegetables might
be there only option.. .which is an excellent option overall.
1) Do you feel research has been convincing enough to state claims and specific regimens to
a vulnerable subgroup of people yes, no, undecided (2) Do you feel research has been done
and proven that you will not be doing peripheral damage to people in certain megadosing
vitamin therapy. yes, no, undecided
I don't understand the push for supplement with lutein and now there is a push for
Preservision which doesn't contain Lutein. I don't understand why. I would like to have a
copy of the results of your study.
Basing current recommendations on National Eye Institute longitudinal study substantiating
that approximately 25% of people with beginning macular degeneration can benefit from
antioxidants and zinc supplements.
There is too much confusion already amongst patients (especially the elderly) who are
relying on info fiom different sources (MDs, ODs, RPhslTV, Radio, Newsprint, Advertising,
word-of-mouth, etc) Even Ocuvite is in different formulations: The high dose AREDS
formula vs a 100% USRDA & Lutein formulation. These people tend to believe almost
anything they are told, but also most are on fixed incomes and cannot afford extensive &
EXPEN$IVE supplements that just are not necessary! !! *Anyone concerned enough to ask, I
recommend they take a regular multivitamin & eat their "green leafy veggies." The AREDS
formula was of limited value & only to those with advanced AMD in one eye, but not the
other yet, or moderate AMD - so those are the ones I recommend the higher dosing to - with
important reservations [underlined three times]! Those who smoke (vs Quit Smoking!) or
live with smokers + Zinc only - warnings on interactions of OTC meds, supplements, &
Rx'd meds. - warnings on possibly depleting copper by taking high dose zinclas well as the
vitamin Ameta C & Smoking risks. I also ALWAYS advise them to ALSO check with their
regular physician in case he knows of any meds or complications that contraindicate these
supplements that the patient neglected to inform me they have. Many elderly seem to already
be trying folk medicines & supplements with varying sources and RISKS. They are being
TARGETS for SNAKE OIL & Mumbo Jumbo far too much for my liking - Sony I got on
my soap box!
My nutritional counseling is limited to: (1) General nutritional info commonly accepted - eg
eating a balanced diet perhaps weighted to fruits & veggies (2) AREDS study: specific
supplements&o for those diagnosed with non exudative AMD who want to do everything
possible, that was produced by NEI study, to prevent conversion to exudative AMD & (3)
Input from my very knowledgable o l o g i s t (which can largely be state as #2 above!) i.e.
don't educate on anything that hasn't been validated by good, large scale. Long term study
by reputable investigators with limited monetary gainlinterest.
Of all the studies I have looked at, the AREDS study is probably the only good well
controlled nutritional study looking at AMD and nutrition. This study did not look at lutein or
zaxanthin. Therefore, a lot of us in the eye care fields are recommending the nutritional
supplements used in the AREDS study. Certainly there is growing evidence that other
supplements such as lutein or zeaxanthin may work as well or better, but historical and
population studies have way too many uncontrolled variables. Therefore, until we get better
more controlled studies, Lutein and zeaxanthin become just one of the list of supplements
along with many vitamins, minerals, and other antioxidants. Therefore, the questions
regarding the recommendations of these compounds are yes they are and can be
recommended but not exclusive of other supplements.
Bilbeny enhances circulation in the eye. WE always recommend bilbeny be in a supplement
or taken separately. CoQlO is also useful in helping the eye to repair oxidative damage.
Since finding lutein or zeaxanthin as a stand-alone product is very difficult, I would ask
about this as apart of another supplement in addition to the current questions.